Geom 4point1
- 1. 4.1 Triangles and Angles Objectives: - Classify triangles by their sides and angles - Find angle measures
- 2. Names of Triangles - by sides Equilateral 3 congruent sides Isosceles At least 2 congruent sides Scalene No congruent sides
- 3. Names of Triangles - by angles Acute 3 acute angles Equilateral 3 congruent angles Right 1 right angle Obtuse 1 obtuse angle
- 4. When you classify a triangle... Be as specific as possible. acute scalene A B C 65Ëš 57Ëš 58Ëš
- 5. When you classify a triangle... What is this one? obtuse isosceles 120Ëš
- 6. Terms Each of the 3 points joining the sides of a triangle is a vertex 2 sides sharing a common vertex are adjacent sides A B C
- 7. Right Triangles In a right triangle, the side opposite the right angle is called the hypotenuse The sides opposite the two acute angles are called legs A B C 50° q r s
- 8. Isosceles Triangles If an isosceles triangle has 3 congruent sides, it is equilateral. If an isosceles triangle has 2 congruent sides, the sides are the legs of the triangle, and the 3rd side is the base of the triangle.
- 9. Identifying parts What kind of triangle is this? isosceles right Which side is the hypotenuse? Which side is the base? Which sides are the legs? 5” 5” 7”
- 10. Interior & Exterior Angles Interior angles are inside the triangle. Exterior angles are adjacent to the interior angles. Each vertex has a pair of congruent exterior angles.
- 11. Triangle Sum Theorem The sum of the measures of the interior angles of a triangle is 180Ëš.
- 12. Exterior Angle Theorem The measure of an exterior angle of a triangle is equal to the sum of the measures of the two nonadjacent interior angles.
- 13. Corollary A corollary to a theorem is a statement that can be proved easily using the theorem.
- 14. Corollary to the Triangle Sum Theorem: The acute angles of a right triangle are complementary.
- 15. Classwork Do p. 198 1-15 together