Download Isosceles triangles are defined as having .

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 of 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) ___________
Find the value of x.
3) x = _____
4) x = _____
5) x = _____
6) x = _____
7)
x = _____
8) x = _____
9) Given: BC  AC; m 1 = 140, find:
m2: _____
m3: _____
m4: _____
10) Given:
Prove:
BC  DC;
BF  DE
1  2
Statements
Reasons
1) __________________
1) __________________
2) __________________
2) __________________
3) ______  ______
3) __________________
4) __________________
4) __________________