Mathematics important points and formulas 2009

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Mathematics
Important points and formulas

Third Edition (May 2009)

Content
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Topic / sub topic
Natural numbers
Whole Numbers
Integers
Rational Numbers
Irrational Numbers
Terminating Decimals
Recurring Decimals
Significant figures
Decimal Places
Standard Form
Conversion Factors
Time
Percentages
Simple Interest
Compound Interest
Speed, Distance and Time
Quadratic Equations
Expansion of algebraic expressions
Factorization of algebraic expressions
Ordering
Variation
PYTHAGORAS’ THEOREM
Area and Perimeter
Surface Area and Volume
Angles on a straight line
Vertically opposite angles
Different types of triangles
Parallel Lines
Types of angles
Angle properties of triangle
Congruent Triangles
Similar Triangles
Areas of Similar Triangles
Polygons
Similar Solids
CIRCLE
Chord of a circle
Tangents to a Circle
Laws of Indices
Solving Inequalities
TRIGONOMETRY
Bearing
Cartesian co-ordinates
Distance – Time Graphs
Speed – Time Graphs
Velocity
Acceleration
SETS

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Loci and construction
Vectors
Column Vectors
Parallel Vectors
Modulus of a Vector
MATRICES
The Inverse of a Matrix
Transformations
Transformation by Matrices
STATISTICS
Probability
Symmetry

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NUMBER
Natural Numbers: Numbers which are used for
counting purpose are called natural numbers.
Ex: 1, 2, 3, 4, …………….100, ……………….
Whole Numbers: Natural numbers including 0 are
called Whole Numbers.
Ex: 0, 1, 2, 3, 4, ……………………..
Integers: Positive natural numbers, negative natural
numbers along with 0 are called integers.
Ex.: …………………, -4, -3, -2, -1, 0, 1, 2, 3, 4, ……………
Rational Numbers: Numbers which are in the form
𝑝
of 𝑞 (q ≠ 0) where p and q are positive or negative
whole numbers are called rational numbers.
1 3 −5 49
Ex: 2 , 4 , 7 , −56 …………………..
Irrational Numbers: Numbers like 2 , 𝜋 cannot
be expressed as rational numbers. Such types of
numbers are called as irrational numbers.
Ex:
5 , 17 , ………….
Terminating Decimals
These are decimal numbers which stop after a
certain number of decimal places.
For example,7/8 = 0.875, is a terminating decimal
because it stops (terminates) after 3 decimal places.
Recurring Decimals
These are decimal numbers which keep repeating a
digit or group of digits; for example
137/259,=0.528 957 528 957 528 957 ...., is a
recurring decimal. The six digits 528957 repeat in
this order. Recurring decimals are written with dots
over the first and last digit of the repeating digits,
e.g. 0.528 957





The order of operations follows the BODMAS
rule:
Brackets
Powers Of
Divide
Multiply
Add
Subtract
Even numbers: numbers which are divisible
by 2, eg, 2, 4, 6, 8, …
Odd numbers: numbers which are not
divisible by 2, eg; 1, 3, 5, 7 …

 Real numbers are made up of all possible














rational and irrational numbers.
An integer is a whole number.
A prime number is divisible only by itself and
by one (1). 1 is not a prime number. It has
only two factors. 1 and the number itself.
The exact value of rational number can be
written down as the ratio of two whole
numbers.
The exact value of an irrational number
cannot be written down.
A square number is the result of multiplying
a number by itself.
Ex: 12, 22, 32, ……………. i.e. 1, 4, 9, ……………..
A cube number is the result of multiplying a
number by itself three times.
Ex: 13, 23, 33, …………………. i.e. 1, 8, 27,………
The factors of a number are the numbers
which divide exactly into two.
eg. Factors of 36
1, 2, 3, 4, 6, 9, 12, 18
Multiples of a number are the numbers in its
times table.
eg. Multiples of 6 are 6, 12, 18, 24, 30, …

Significant figures;
Example;
8064 = 8000 (correct to 1 significant figures)
0.00508 =0.005 (correct to 1 significant figures)
0.00508 = 0.0051 (correct to 2 significant figures)
2.00508 = 2.01 (correct to 3 significant figures)
Decimal Places
Example
0.0647 = 0.1 (correct to 1 decimal places)
Standard Form:
The number a x 10n is in standard form when
1≤ a < 10 and n is a positive or negative integer.
Eg: 2400 = 2.4 x 103
0.0035 = 3.5 x 10-3

____________________________________________________________________________________
Mathematics - important points and formulas 2009

mohd.hilmy@gmail.com

Page 1 of 21

Conversion Factors:
Length:
1 km = 1000 m
1 m = 100 cm
1 cm = 10 mm

𝑘𝑚 means kilometer
𝑚 means meter
𝑐𝑚 means centimeter
𝑚𝑚 means millimeter

Mass:
1 kg = 1000 gm
1 gm = 1000 mgm
1 tonne = 1000 kg

where kg means kilogram
gm means gram
mgm means milligram

Volume:
1 litre
= 1000 cm3
1 m3
= 1000 litres
1 kilo litre = 1000 litre
1 dozen = 12

Time:
1 hour = 60 minutes = 3600
seconds
1 minute = 60 seconds.
1 day = 24 hours
1 year = 12 months
= 52 weeks
= 365.25 days.

1 week = 7 days
1 leap year = 366 days
1 light year = 9.46 × 1012 km.

Percentages:
 Percent means per hundred.
 To express one quantity as a percentage of another, first write the first quantity as a fraction of
the second and then multiply by 100.
 Profit = S.P. – C.P.
 Loss = C.P. – S.P.
𝑆𝑃−𝐶𝑃
 Profit percentage = 𝐶𝑃 × 100


Loss percentage =

where CP = Cost price

𝐶𝑃−𝑆𝑃
𝐶𝑃

× 100

and SP = Selling price

Simple Interest:
To find the interest:


𝑖=

𝑃𝑅𝑇

100

Compound Interest:
r

A = 𝑝 1 + 100

where

P = money invested or borrowed
R = rate of interest per annum
T = Period of time (in years)
To find the amount:

𝐴 = 𝑃 + 𝐼

where A = amount

n

Where,
𝑨 stands for the amount of money accruing after 𝑛
year.
𝑷 stands for the principal
𝑹 stands for the rate per cent per annum
𝒏 stands for the number of years for which the
money is invested.

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Page 2 of 21

Speed, Distance and Time:
 Distance = speed x time
 Speed =
 Time =

 Units of speed: km/hr, m/sec
 Units of distance: km, m
 Units of time:
hr, sec

𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑡𝑖𝑚𝑒
𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒

5
= m / sec
18
18
 m / sec ×
= km / hr
5

 Average speed =

D

 km / hr ×

𝑆𝑝𝑒𝑒𝑑
𝑡𝑜𝑡𝑎𝑙 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑡𝑜𝑡𝑎𝑙 𝑡𝑖𝑚𝑒

S

T

ALGEBRA
Quadratic Equations:
An equation in which the highest power of the variable is 2 is called quadratic equation. Thus
ax2 + bx + c = 0 where a, b, c are constants and a ≠ 0 is a general equation.
Solving quadratic equations:
We can solve quadratic equation by method of,
a) Factorization
b) Using the quadratic formula
c) Completing the square
(a) Solution by factors:
Consider the equation c × d = 0, where c and d are numbers. The product c × d can only be zero if either c
or d (or both) is equal to zero.
i.e. c = 0 or d = 0 or c = d = 0.
(b)Solution by formula:
The solutions of the quadratic equation
ax2 + bx + c = 0 are given by the formula:
𝑥 =

−𝑏± 𝑏 2 −4𝑎𝑐

2𝑎
(c) Completing the square

 Make the coefficient of x2 , i.e. a = 1
 Bring the constant term, i.e. c to the right side of equation.
𝑏
 Divide coefficient of x, i.e. by 2 and add the square i.e. ( 2)2 to both sides of the equation.
 Factorize and simplify answer
Expansion of algebraic expressions

𝑎 𝑏 + 𝑐 = 𝑎𝑏 + 𝑎𝑐

(a + b)2 = a2 + 2ab + b2

(a – b)2 = a2 – 2ab + b2

a2 + b2 = (a + b)2 – 2ab

a2 – b2
= (a + b)(a – b)
Ordering:
= is equal to
≠ is not equal to
> is greater than

Factorization of algebraic expressions




𝑎2 + 2𝑎𝑏 + 𝑏 2 = (𝑎 + 𝑏)2
𝑎2 − 2𝑎𝑏 + 𝑏 2 = (𝑎 − 𝑏)2
𝑎2 − 𝑏 2 = 𝑎 + 𝑏 (𝑎 − 𝑏)

≥ is greater than or equal to
< is less than
≤ is less than or equal to

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Page 3 of 21

Variation:
Direct Variation:
y is proportional to x

Inverse Variation:
y is inversely proportional to x
1
y
x
k
y=
x

y x
y = kx
MENSURATION
PYTHAGORAS’ THEOREM

For all the right angled triangles “ the square on the hypotenuse is equal to the
sum of the squares on the other two sides”
𝑐 2 = 𝑎2 + 𝑏 2

𝒄=

𝑎2 + 𝑏 2

𝒃=

Area and Perimeter:
Figure
Rectangle

𝑐 2 − 𝑎2

𝒂=

Diagram

𝑐 2 − 𝑏2

Area
b

Perimeter

Area = l × b

perimeter = 2( 𝑙 + 𝑏 )

Area = side × side
= a×a

perimeter = 4 × side
=4×a

l
a

Square
a

a
a

Parallelogram

Area = b × h
perimeter = 2(a + b )
Area = ab sin 𝜃
where a, b are sides and 𝜃 is
the included angle

Triangle
Area =

1
2

× 𝑏𝑎𝑠𝑒 × 𝑕𝑒𝑖𝑔𝑕𝑡
1

Area = 2 𝑎𝑏 𝑠𝑖𝑛 𝐶
= 𝑠 𝑠− 𝑎
where s =

perimeter = a + b + c

𝑠 − 𝑏 (𝑠 − 𝑐)
𝑎+𝑏+𝑐
2

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Page 4 of 21

Trapezium
1

Area = 2 𝑎 + 𝑏 𝑕

perimeter = Sum of all
sides

Circle
r

Area =  r2

Semicircle
r
Sector

𝑟
𝜃

Surface Area and Volume:
Figure
Diagram
Cylinder

Area =

1 2
r
2


2
Area =  r  360

1
perimeter =  d + d
2

length of an arc = 2 r 

Surface Area
curved surface area = 2πrh
total surface area = 2πr(h + r)

Cone

circumference = 2  r

curved surface area = 𝜋𝑟𝑙
where l = (r 2  h 2 )
total surface area = 𝜋𝑟(𝑙 + 𝑟)

Sphere
Surface area = 4πr2

Pyramid
Base area + area of the shapes in
the sides


360

Volume
2
Volume =  r h

Volume =

1 2
πr h
3

Volume =

4 3
πr
3

1
× base area ×
3
perpendicular height

Volume =

Cuboid
Surface area = 2(𝑙𝑏 + 𝑏𝑕 + 𝑙𝑕)

Cube

Hemisphere

Volume = 𝑙 × 𝑏 × 𝑕

Surface area = 6𝑙 2

Volume = 𝑙 3

Curved surface area = = 2 r2

Volume =

2 3
r
3

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Page 5 of 21

GEOMETRY
(a) Angles on a straight line
The angles on a straight line add up to 180o.

Parallel Lines:
When lines never meet, no matter how far they are
extended, they are said to be parallel.

x + y + z =180o



Vertically opposite angles are equal.
a = c; b = d; p = s and q =r



(b) Angle at a point

Corresponding angles are equal.
𝑎 = 𝑞; 𝑏 = 𝑝; 𝑐 = 𝑟 and 𝑑 = 𝑠
Alternate angles are equal.
c= q and d = p.
Sum of the angles of a triangle is 180o.
Sum of the angles of a quadrilateral is 360o.


The angles at a point add up to 360o.
a + b + c + d = 360o




(c) Vertically opposite angles
If two straight line intersect, then
𝑎= 𝑐
𝑏 = 𝑑 (Vert,opp.∠𝑠)

Types of angles
Given an angle , if
𝜃 < 90° , then 𝜃 is an acute angle

90° < 𝜃 < 180° , then 𝜃 is an obtuse angle

180° < 𝜃 < 360° , then 𝜃 is an reflex angle

Triangles
Different types of triangles:
1. An isosceles triangle has 2 sides and 2 angles the same.

AB = AC
ABC = BCA

2. An equilateral triangle has 3 sides and 3 angles the same.
AB = BC = CA and ABC = BCA = CAB

3. A triangle in which one angle is a right angle is called the right angled triangle.
ABC = 90o
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Page 6 of 21

Angle properties of triangle:
 The sum of the angles of a triangle is equal to 180o.
 In every triangle, the greatest angle is opposite to the longest side. The smallest angle is
opposite to the shortest side.
 Exterior angle is equal to the sum of the opposite interior angles.
x=a+b

Congruent Triangles:
Two triangles are said to be congruent if they are equal in every aspect.

a = x
b = y
c = z

AB = XY
BC = YZ
AC = XZ

Similar Triangles:
If two triangles are similar then they have a pair of corresponding equal angles and the three ratios of
corresponding sides are equal.

AB
BC
AC
=
=
XY
YZ
XZ

 a =  x;  b =  y and  c =  z

If you can show that one of the following conditions is true for two triangles, then the two triangles are
similar.
i)
The angles of one triangle are equal to the corresponding angles of the other triangle.

∆ ABC is similar to ∆ XYZ because  a=  x;  b =  y and  c =  z
ii) The ratio of corresponding sides is equal.

F

R
D
P

If

PQ PR
QR
=
=
DE DF
EF

then ∆ PQR is similar to ∆ DEF

Q

E

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Page 7 of 21

iii)

The ratios of the corresponding sides are equal and the angles between them are equal.
R

Z

Y

X
P

Q

∆ PQR is similar to ∆ XYZ (if, for eg:  P =  X and

PQ PR
=
)
XY XZ

Areas of Similar Triangles:
The ratio of the areas of similar triangles is equal to the ratio of the square on corresponding sides.
C
R

A

B

P

Q

AC 2
area of ABC AB 2
BC 2
=
=
=
area of PQR PQ 2 QR 2
PR 2

Polygons:
i)
The exterior angles of a polygon add up to 360o.
ii)
The sum of the interior angles of a polygon is (𝑛 – 2) × 180o where 𝑛 is the number of sides
of the polygon.
iii)
A regular polygon has equal sides and equal angles.
iv)
v)

360

If the polygon is regular and has 𝑛 sides, then each exterior angle = 𝑛
3 sides = triangle
6 sides = hexagon
9 sides = nonagon

4 sides = quadrilateral
7 sides = heptagon
10 sides = decagon

5 sides = pentagon
8 sides = octagon

Similar Solids:
If two objects are similar and the ratio of corresponding sides is k, then
 the ratio of their areas is 𝑘2.
 the ratio of their volumes is 𝑘3.
Length
𝑙1
𝑟
= 1
𝑙2
𝑟2

=

𝑕1
𝑕2

Area
2
2
A1
r
h
= 12 = 12
A2
r2
h2

Volume
3
3
V1
r
h
= 13 = 13
V2
r2
h2

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Page 8 of 21

CIRCLE
 The angle subtended by an arc at the centre is twice the angle subtended at the circumference





The angle in a semi-circle is a right angle. [or if a triangle is inscribed in a semi-circle the angle
opposite the diameter is a right angle]. ∠𝐴𝑃𝐵 = 90°





Angles subtended by an arc in the same segment of a circle are equal.

Opposite angles of a cyclic quadrilateral add up to 180o (supplementary). The corners touch the
circle. A+C = 180o, B+D 180o

The exterior angle of a cyclic quadrilateral is equal to the interior opposite angle.(𝑏 = 𝑝)

Chord of a circle:
A line joining two points on a circle is called a chord.
The area of a circle cut off by a chord is called a segment.
AXB is the minor arc and AYB is the major arc.
a) The line from the centre of a circle to the mid-point of
a chord bisects the chord at right angles.
b) The line from the centre of a circle to the mid-point of a
chord bisects the angle subtended by the chord at the centre of the circle.
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Page 9 of 21

Tangents to a Circle:
 The angle between a tangent and the radius drawn to
the point of contact is 90o.

 ABO = 900



From any point outside a circle just two tangents to the circle may be drawn and they are of
equal length.
TA = TB



Alternate Segment Theorem
The angle between a tangent and a chord through the point
of contact is equal to the angle subtended by the chord
in the alternate segment.

 QAB =  ACB (p = q)



TC2 = AC × BC

P

T

INDICES:


am × an = am + n



am ÷ an = am – n



(am)n = amn



a0 = 1



a-n =







=

 a

m

n

am
bm

m

= am / n



1
an
m

a
 
b

m

m

(a × b) = a × b

a× b

=



a
b

=



 a

2

ab
a
b
= a

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Page 10 of 21

Solving Inequalities:
When we multiply or divide by a negative number the inequality is reversed.
Eg: 4 > -2
By multiplying by -2 [4(-2) < (-2)(-2) ]
-8 < +4
TRIGONOMETRY
Let ABC be a right angled triangle, where  B = 90o



Sin 𝜃 =



Cos 𝜃 =



Tan 𝜃 =

𝑂𝑝𝑝𝑜𝑠𝑖𝑡𝑒 𝑆𝑖𝑑𝑒
𝐻𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒

=

𝐴𝑑𝑗𝑎𝑐𝑒𝑛𝑡 𝑆𝑖𝑑𝑒
𝐻𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒
𝑂𝑝𝑝𝑜𝑠𝑖𝑡𝑒 𝑠𝑖𝑑𝑒
𝐴𝑑𝑗𝑎𝑐𝑒𝑛𝑡

𝑆𝑖𝑑𝑒

=
=

𝑂
𝐻
𝐴

SOH CAH TOA

𝐻
𝑂
𝐴

Sine Rule:
a
b
c
=
=
sin A sin B sin C
Cosine Rule:
To find the length of a side:
 a2 = b2 + c2 - 2bc cosA


b2 = a2 + c2 – 2ac cos B



c2 = a2 + b2 – 2ab cos C

To find an angle when all the three sides are
given:

b2  c2  a2
 cos A =
2bc
2
a  c2 b2
 cos B =
2ac
2
a  b2  c2
 cos C =
2ab

Bearing
The bearing of a point B from another point A is;
(a) an angle measured from the north at A.
(b) In a clockwise direction.
(c) Written as three-figure number (i.e. from 000 ° to 360°)
Eg: The bearing of B from A is 050° .

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Page 11 of 21

Cartesian co-ordinates
Gradient and equation of a straight line
The gradient of the straight line joining any two given points A( x1 , y1 ) and B( x2 , y2 ) is;
y  y1
m 2
x2  x1
The gradient/intercept form of the equation of a straight line is y  mx  c , where m  gradient and
c  intercept on y – axis.



The midpoint of the line joining two points A( x1 , y1 ) and B( x2 , y2 ) is; 𝑀 =




The distance between two points A( x1 , y1 ) and B( x2 , y2 ) is; 𝐴𝐵 =
Parallel lines have the same gradient.



In a graph, gradient =

Vertical height
or
Horizontal height

𝑥 1 +𝑥 2

𝑥2 − 𝑥1

2
2

,

𝑦 1 +𝑦 2
2

+ 𝑦2 − 𝑦1

2

𝑦
𝑥

Distance – Time Graphs:
From O to A : Uniform speed
From B to C : uniform speed
From A to B : Stationery (speed = 0)

The gradient of the graph of a distance-time graph gives the speed of the moving body.

Speed – Time Graphs:
From O to A : Uniform speed
From A to B : Constant speed (acceleration = 0)
From B to C : Uniform deceleration / retardation

The area under a speed –time graph represents the distance
travelled.
The gradient of the graph is the acceleration. If the acceleration is
negative, it is called deceleration or retardation. (The moving body is slowing down.)
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Page 12 of 21

Velocity:
Velocity is the rate of change of distance with respect to the time.
Acceleration:
Acceleration is the rate of change of velocity with respect to time.

SETS:
Notations
 𝜉 = universal set
 ∪ (union) = all the elements
 ∩ (intersection) = common elements
 Ø or { } = empty set
 ∈ = belongs to
 ∉ = does not belongs to
 ⊆ = Subset
Subset ⊆
𝐵 ⊆ 𝐴 means every elements of set B is also an
element of set A.





𝐴′ = compliment of A (i.e. the elements of
𝜉 - the elements of A)
n(A) = the number of elements in A.
De Morgan’s Laws: (𝐴 ∪ 𝐵)′ = (𝐴′ ∩ 𝐵 ′ )
(𝐴 ∩ 𝐵)′ = (𝐴′ ∪ 𝐵 ′ )

Proper subset ⊂
B ⊂ A means every element of B is an element
of set A but B≠A.

or

Disjoint sets
Disjoint set do not have any element in
common. If A and B are disjoint sets, then
𝐴∩ 𝐵=∅

Union ∪
𝐴 ∪ 𝐵 is the set of elements in either A , B or
both A and B.

Intersection ∩
𝐴 ∩ 𝐵 is the set of elements which are in A
and also in B

Complement
The complement of A, written as 𝐴′ refers to
the elements in 𝜀 but not in A.

____________________________________________________________________________________


Page 13 of 21

Loci and construction
The locus of a point is a set of points satisfying a given set of conditions.
(a) Locus of points at a distance x from a given point, O.
Locus: The circumference of a circle centre O, radius x.
(b) Locus of a points at a distance x from a straight line AB

Locus: A pair of parallel lines to the given line AB.
(c) Locus of points equidistance between 2 points.
Locus: Perpendicular bisector of the two points.

(d) Locus of points equidistant from two given lines AB and AC
Locus: Angle bisector of ∠𝐵𝐴𝐶

Vectors:


A vector quantity has both magnitude and direction.
a



Vectors a and b represented by the line segments can be added
using the parallelogram rule or the nose- to- tail method.




b
A scalar quantity has a magnitude but no direction. Ordinary numbers are scalars.
The negative sign reverses the direction of the vector.
The result of a – b is a + -b
i.e. subtracting b is equivalent to adding the negative of b.

Addition and subtraction of vectors
𝑂𝐴 + 𝐴𝐶 = 𝑂𝐶 (Triangular law of addition)
𝑂𝐵 + 𝑂𝐴 = 𝑂𝐶 ( parallelogram law of addition)

____________________________________________________________________________________


Page 14 of 21

Column Vectors:
The top number is the horizontal component and the bottom number is the vertical component
 x
 
 y
 
Parallel Vectors:
 Vectors are parallel if they have the same direction. Both components of one vector must be
in the same ratio to the corresponding components of the parallel vector.
a
a
 In general the vector k   is parallel to  
b
b
 
 
Modulus of a Vector:
The modulus of a vector a, is written as a and represents the length (or magnitude) of the vector.

 m
In general, if x =   , x =
n
 

(m 2  n 2 )

MATRICES:
Addition and Subtraction:
Matrices of the same order are added (or subtracted) by adding (or subtracting) the corresponding
elements in each matrix.
a b   p q a  p b  q

 c d  +  r s  =  c  r d  s
 
 


 
 


a b   p q a  p b  q

c d  -  r s  =  c  r d  s
 
 


 
 


Multiplication by a Number:
Each element of a matrix is multiplied by the multiplying number.
 a b   ka kb 
k× 
 c d  =  kc kd 
 


 


Multiplication by another Matrix:
Matrices may be multiplied only if they are compatible. The number of columns in the left-hand matrix
must equal the number of rows in the right-hand matrix.

 a b   p q   ap  br aq  bs 

 c d  ×  r s  =  cp  dr cq  ds 
 
 


 
 



In matrices A2 means A × A. [you must multiply the matrices together]

____________________________________________________________________________________


Page 15 of 21

The Inverse of a Matrix:
1
a b 
 then A-1 =
If A = 
c d 
(ad  bc)



 d  b

 c a 







AA-1 = A-1A = I where I is the identity matrix.
The number (ad – bc ) is called the determinant of the matrix and is written as A



If A = 0, then the matrix has no inverse.

 Multiplying by the inverse of a matrix gives the same result as dividing by the matrix.
e.g.
if AB = C
A-1AB = A-1C
B = A-1C
 x
r
xr
 If C =   and D =   then C + D = 
 y
s
 y  s

 
 


Transformations:
a) Reflection:
When describing a reflection, the position of the mirror line is essential.
b) Rotation:
To describe a rotation, the centre of rotation, the angle of rotation and the direction of rotation
are required.
A clockwise rotation is negative and an anticlockwise rotation is positive.
>> (angle) (Direction)rotation about (centre)

c) Translation:
When describing a translation it is necessary to give the translation vector





 x
 
 y
 

+ x represents movement to the right
- x represents movement to the left
+ y represents movement to the top
- y represents movement to the bottom.

>> Translation by the column vector -----

d) Enlargement:
To describe an enlargement, state;
i.

The scale factor, K

ii.

The centre of enlargement (the invariant point)

Scale factor =

length of the image
length of the object

>> Enlargement by the scale factor --- centre ------



If K > 0, both the object and the image lie on the same side of the centre of enlargement.



If K < 0, the object and the image lie on opposite side of the centre of enlargement.



If the scale factor lies between 0 and 1, then the resulting image is smaller than the object.
[although the image is smaller than the object, the transformation is still known as an
enlargement]

Area of image = K2 area of object

____________________________________________________________________________________


Page 16 of 21

Repeated Transformations:
XT(P) means ‘perform transformation T on P and then perform X on the image.’
XX(P) may be written X2(P).
Inverse Transformations:
The inverse of a transformation is the transformation which takes the image back to the object.
 x
 x
If translation T has a vector   , then the translation which ahs the opposite effect has vector   .
 y
 y
 
 
This is written as T-1.
If rotation R denotes 90o clockwise rotation about (0, 0), then R-1 denotes 90o anticlockwise rotation
about (0, 0).
For all reflections, the inverse is the same reflection.
Base vectors
1
0
The base vectors are considered as I =   and J =  
0
1
 
 
The columns of a matrix give us the images of I and J after the transformation.
Shear:
Shear factor =

𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑎 𝑝𝑜𝑖𝑛𝑡 𝑚𝑜𝑣𝑒𝑠 𝑑𝑢𝑒 𝑡𝑜 𝑡𝑕𝑒 𝑠𝑕𝑒𝑎𝑟
𝑃𝑒𝑎𝑝𝑒𝑛𝑑𝑖𝑐𝑢𝑙𝑎𝑟

𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑜𝑓 𝑡𝑕𝑒 𝑝𝑜𝑖𝑛𝑡 𝑓𝑟𝑜𝑚 𝑡𝑕𝑒 𝑓𝑖𝑥𝑒𝑑 𝑙𝑖𝑛𝑒

=

𝑎
𝑏

[The shear factor will be the same calculated from any point on the object with the exception of those
on the invariant line]

Area of image = Area of object

Stretch:
To describe a stretch, state;
i.

the stretch factor, p

ii.

the invariant line,

iii.

the direction of the stretch
(always perpendicular to the invariant line)

Scale factor =

𝑃𝑒𝑟𝑝𝑒𝑛𝑑𝑖𝑐𝑢𝑙𝑎𝑟

𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑜𝑓 𝐶 ′ 𝑓𝑟𝑜𝑚 𝐴𝐵

𝑃𝑒𝑎𝑝𝑒𝑛𝑑𝑖𝑐𝑢𝑙𝑎𝑟

𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑜𝑓 𝐶 𝑓𝑟𝑜𝑚 𝐴𝐵

Where, P is the stretch factor

Area of image = 𝑝 × Area of object

____________________________________________________________________________________


Page 17 of 21

Transformation by Matrices
Reflection
Matrix
1 0
0 −1
−1 0
0 1
0 1
1 0
0 −1
−1 0

Transformation
Reflection in the x-axis
Reflection in the y-axis
Reflection in the line y = x
Reflection in the line y = - x

Rotation
Matrix

Angle

Direction

centre

0 −1
1 0

90°

anticlockwise

(0, 0)

90°

clockwise

(0, 0)

180°

Clockwise/ anticlockwise

(0, 0)

0
−1
−1
0

1
0
0
−1

Enlargement
𝑘
0

0
where 𝑘= scale factor and centre of enlargement = (0, 0)
𝑘

Stretch
Matrix

Stretch factor

Invariant line

Direction

𝑘
0

0
1

𝑘

y-axis

Parallel to x - axis

1
0

0
𝑘

𝑘

x - axis

Parallel to y - axis

Shear factor

Invariant line

Direction

𝑘

x-axis

Parallel to x - axis

𝑘

y - axis

Parallel to y - axis

Shear
Matrix
1 𝑘
0 1
1 0
𝑘 1

____________________________________________________________________________________


Page 18 of 21

STATISTICS
Bar Graph:
A bar chart makes numerical information easy to see by showing it in a pictorial form.
The width of the bar has no significance. The length of each bar represents the quantity.

Pie Diagram:
The information is displayed using sectors of a circle.

Histograms:
A histogram displays the frequency of either continuous or grouped discrete data in the form of bars.
The bars are joined together.
The bars can be of varying width.
The frequency of the data is represented by the area of the bar and not the height.
[When class intervals are different it is the area of the bar which represents the frequency not the
height]. Instead of frequency being plotted on the vertical axis, frequency density is plotted.
𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦

Frequency density =

𝑐𝑙𝑎𝑠𝑠 𝑤𝑖𝑑𝑡 𝑕

Mean:
The mean of a series of numbers is obtained by adding the numbers and dividing the result by the
number of numbers.
Mean =

 fx
f

where ∑ fx means ‘the sum of the products’
i.e. ∑ (number × frequency)
and ∑f means ‘ the sum of the frequencies’.

Median:
The median of a series of numbers is obtained by arranging the numbers in ascending order and then
choosing the number in the ‘middle’. If there are two ‘middle’ numbers the median is the average
(mean) of these two numbers.

Mode:
The mode of a series of numbers is simply the number which occurs most often.

Frequency tables:
A frequency table shows a number x such as a score or a mark, against the frequency f or number of
times that x occurs.
____________________________________________________________________________________


Page 19 of 21

Cumulative frequency:
Cumulative frequency is the total frequency up to a given point.
Cumulative frequency Curve:

A cumulative frequency curve shows the median at the 50 th percentile of the cumulative frequency.
The value at the 25th percentile is known as the lower quartile and that at the 75 th percentile as the
upper quartile.
A measure of the spread or dispersion of the data is given by the inter-quartile range where
inter-quartile range = upper quartile – lower quartile.
Probability:
 Probability is the study of chance, or the likelihood of an event happening.
𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑓𝑎𝑣𝑜𝑢𝑟𝑎𝑏𝑙𝑒

𝑜𝑢𝑡𝑐𝑜𝑚𝑒𝑠



Probability of an event =






If the probability = 0 it implies the event is impossible
If the probability = 1 it implies the event is certain to happen.
All probabilities lie between 0 and 1.
Probabilities are written using fractions or decimals.

𝑇𝑜𝑡𝑎𝑙 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑒𝑞𝑢𝑎𝑙𝑙𝑦 𝑙𝑖𝑘𝑒𝑙𝑦 𝑜𝑢𝑡𝑐𝑜𝑚 𝑒

Exclusive events:
Two events are exclusive if they cannot occur at the same time.
The OR Rule:
For exclusive events A and B
p(A or B) = p(A) + p(B)
Independent events:
Two events are independent if the occurrence of one even is unaffected by the occurrence of the other.
The AND Rule:
p(A and B) = p(A) × p(B)
where p(A) = probability of A occurring
p(B) = probability of B occurring

Tree diagrams:
A tree diagram is a diagram used to represent probabilities when two or more events are combined.
____________________________________________________________________________________


Page 20 of 21

Symmetry:
 A line of symmetry divides a two-dimensional shape into two congruent (identical) shapes.


A plane of symmetry divides a three-dimensional shape into two congruent solid shapes.



A two-dimensional shape has rotational symmetry if, when rotated about a central point, it fits
its outline. The number of times it fits its outline during a complete revolution is called the order
of rotational symmetry.
Shape
Square
Rectangle
Parallelogram
Rhombus
Trapezium
Kite
Equilateral Triangle
Regular Hexagon

Number of Lines
of Symmetry
4
2
0
2
0
1
3
6

Order of Rotational
Symmetry
4
2
2
2
1
1
3
6

This book is :
Compiled by: Mohamed Hilmy
Mathematics Teacher
H Dh. Atoll School
Proof read by: Mohamed Hilmy
Lijo George
Mathematics Department
H Dh. Atoll School
For any inquiry feel free to call to these numbers or mail to the following addresses
Contact: +9609807576 or +9607828455, mail: mohd.hilmy@gmail.com
@ H Dh. Atoll School,+9606520056, mail: hdhatollschool@gmail.com
© All rights reserved by Abu-Yooshau 2009.

* Distribute this book freely. NOT FOR SALE.

____________________________________________________________________________________


Page 21 of 21

Mathematics important points and formulas 2009

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Mathematics important points and formulas 2009