1. 1 Isosceles and Equilateral Triangles

2. 2 Parts of an Isosceles Triangle An isosceles triangle is a triangle with two congruent sides. The congruent sides are called legs and the third side is called the base. 3 Leg Base 21 Ð 1 and Ð 2 are base angles Ð 3 is the vertex angle

3. Isosceles Triangle Theorems Example: x ° 50 ° Find the value of x. A B C If two sides of a triangle are congruent, then the angles opposite those sides are congruent.

4. Isosceles Triangle Theorems If two angles of a triangle are congruent, then the sides opposite those angles are congruent. Example:Find the value of x. A B C 50 ° ° 3x - 7 x+15 A B C

5. 5 Equilateral Triangles Equilateral: A triangle in which all 3 sides are equal. G H I GH = 3.7 cm GI = 3.70cm HI = 3.7 cm

6. Equilateral Triangle Theorems If a triangle is equilateral, then it is equiangular. If a triangle is equilateral, then it is equiangular. T S R 15 in. If a triangle is equiangular, then it is equilateral. If a triangle is equiangular, then it is equilateral. What is the length of each side and angle?