GEOMETRY/TRIGONOMETRY 2 Name _______________________
Isosceles triangles are defined as having ___________________________________________.
They have special names for their parts:
________: the two congruent sides
________: the third side
__________ ___________: the angle opposite the base.
__________ ___________: the angles adjacent to the base.
Isosceles Triangle Theorem:
If two sides of a triangle are congruent, then the __________ opposite those sides are
congruent.
If AB AC, then B C
Theorem 4-2 (converse of Isos. Thm):
If two angles of a triangle are congruent, then the __________ opposite those angles are
congruent.
If B C, then AB AC
Corollary 1: An equilateral triangle is also _______________. (and vice versa)
Corollary 2: An equilateral triangle has three _____ angles.
Corollary 3: The bisector or the vertex angle of an isosceles triangle is perpendicular to the
base at its _______________.
Given two congruent parts,
a) Name the
b) Use the Isos. Theorem or its converse to name the sides or angles.
c) State which if you used the theorem or the converse.
1) V Y 2) TZ UZ
a) ________ a) ________
b) _____ ______ b) _____ ______
c) _______________ c) ___________
