Isosceles and Equilateral Triangles Geometry H2 (Holt 4-9) K.Santos

Parts of an Isosceles Triangle Isosceles triangle—is a triangle with at least two congruent sides A B C Legs—are the congruent sides Vertex angle—angle formed by the legs Base—side opposite the vertex angle Base angles—two angles that have the base as a side

Isosceles Triangle Theorem (4-9-1)

Converse of the Isosceles Triangle Theorem (4-9-2)

Example—finding angle measures

Example—finding angle measures (algebraic)

Corollary(4-9-3)— Equilateral Triangle

Corollary (4-9-4)— Equiangular Triangle

Example—Finding angles Find x. G 4x+12 H I

Example—finding sides J Find t. 3t + 3 K 5t – 9 L

Example—Multiple Triangles Find the measures of the numbered angles