Download Section 4.7

Geometry 4.7
BIG IDEA: USE
ISOSCELES AND
EQUILATERAL
TRIANGLES
Isosceles Triangle
Vertex
Leg
Leg
Base
Angles
Base
Theorem 4.7 Base Angles Theorem
IF TWO SIDES OF A TRIANGLE ARE
CONGRUENT, THEN THE ANGLES
OPPOSITE TO THEM ARE CONGRUENT
A
B
C
Theorem 4.8 Converse of Base
Angles Theorem
IF TWO ANGLES OF A TRIANGLE ARE
CONGRUENT, THEN THE SIDES OPPOSITE
THEM ARE CONGRUENT
A
B
C
Corollary to the Base Angles
Theorem
IF A TRIANGLE IS EQUILATERAL , THEN
IT IS EQUIANGULAR
B
A
C
Corollary to the Converse of
Base Angles Theorem
IF A TRIANGLE IS EQUIANGULAR, THEN IT
IS EQUILATERAL
B
A
C
Example: Name two congruent angles.
F
E
D
Example: Complete the statement.
HG @ HK
Ð? @ Ð?
1. If
2. If ÐKHJ
?@?
H
, then
G
@ ÐKJH, then
K
J
Example: Find the measure of ST.
U
5cm
S
T
Example: Find the measures
of
ÐP,ÐQ,ÐR
P
Q
R
Example: Solve for x.
x +3
8