Geometry working with angles
- 2. 1.-DEFINITION AND PARTS ◦ An angle measures the amount of turn. ◦ Parts of an Angle The corner point of an angle is called the vertex And the two straight sides are called arms The angle is the amount of turn between each arm. ANGLES
- 3. 2.-LABELLING ANGLES ◦ There are two main ways to label angles: 1. by giving the angle a name, usually a lower-case letter like a or b, or sometimes a Greek letter like α (alpha) or θ (theta) 2. or by the three letters on the shape that define the angle, with the middle letter being where the angle actually is (its vertex). Example angle "a" is "BAC", and angle "θ" is "BCD" ANGLES
- 4. 3.- NAMES OF ANGLES 3.1. ACUTE ANGLES ◦ An Acute Angle is less than 90° ANGLES
- 5. 3.- NAMES OF ANGLES 3.2. RIGHT ANGLES ◦ A right angle is an internal angle which is equal to 90° ANGLES
- 6. 3.- NAMES OF ANGLES 3.3. OBTUSE ANGLES ◦ An Obtuse Angle is more than 90° but less than 180° ANGLES
- 7. 3.- NAMES OF ANGLES 3.4. STRAIGHT ANGLES ◦ A straight angle is 180 degrees ANGLES
- 8. 3.- NAMES OF ANGLES 3.5. REFLEX ANGLES ◦ A Reflex Angle is more than 180° but less than 360° ANGLES
- 9. ANGLES
- 10. 4.- SUPPLEMENTARY ANGLES ◦ Two Angles are Supplementary if they add up to 180 degrees. These two angles (140° and 40°) are Supplementary Angles, because they add up to 180°. Notice that together they make a straight angle. But the angles don't have to be together. These two are supplementary because 60° + 120° = 180° http://www.mathsisfun.com/geometry/supplementary-angles.html ANGLES
- 11. 5.- COMPLEMENTARY ANGLES ◦ Two Angles are Complementary if they add up to 90 degrees (a Right Angle). These two angles (40° and 50°) areComplementary Angles, because they add up to 90°. Notice that together they make a right angle. But the angles don't have to be together. These two are complementary because 27° + 63° = 90° http://www.mathsisfun.com/geometry/supplementary-angles.html ANGLES
- 12. ◦ 1.-TRANSPORTING ◦ We transport angles with compass ◦ To transport angles with compass, we carry two key measures of the angle: - The radius of the arc - The chord of the arc http://recursostic.educacion.es/artes/plastic/web/cms/index.php ?id=179 WORKING WITH ANGLES
- 13. ◦ 2.-ADDITION ◦ We transport the two angles with compass as before. 4 2 A 1 B 4 3 A B 3 2 1 WORKING WITH ANGLES
- 14. ◦ 2.-SUBTRACTION ◦ We transport the two angles with compass as before. 4 2 A 1 B 3 4 2 A B 3 1 WORKING WITH ANGLES
- 15. Bisector angle is the line segment that divides the angle into two equal parts. http://recursostic.educacion.es/artes/plastic/web/cms/index.ph p?id=190 BISECTOR ANGLES