Isosceles and Equilateral Triangles

Base Angles Theorem•If two sides of a triangle are

congruent (isosceles), then the angles opposite them are congruent.

Converse of the Base Angles Theorem

•If the base angles are congruent, then the sides opposite them are congruent (isosceles triangle).

Find angle K

Equiangular and Equilateral Triangles

•Every side is congruent and every angle is 60 degrees

One angle of an equilateral triangle is (2x + 8). What is the value of x?

Hypotenuse-Leg (HL) Theorem

•If the hypotenuse and leg of one triangle are congruent to the hypotenuse and leg of another triangle, then the two triangles are congruent.

Prove!

Corresponding Parts of Congruent Triangles are

Congruent (CPCTC)

•After two triangles are proven congruent, corresponding parts can be stated as congruent.

Prove AD||CE

Summary

•Write everything you know about isosceles triangles, equilateral and equiangular triangles, and the HL Theorem.