4.5 Isosceles and Equilateral Triangles

Isosceles Triangles At least two sides are of equal length. It also has two congruent angles. Base Angles Base Legs Vertex Angle

Isosceles Triangle Theorem If two sides of a triangle are congruent, the angles opposite them are congruent.

Converse of Isosceles Triangle Theorem If two angles of a triangle are congruent, the sides opposite them are congruent

The bisector of the vertex angle of an isosceles triangle is the perpendicular bisector of the base and bisects

Corollary to Theorem 4.3 If a triangle is equilateral, then the triangle is equiangular x Y Z

Corollary to Theorem 4.4 If a triangle is equiangular, then the triangle is equilateral x Y Z