Download Isosceles Triangles

Section 4.3
Warm Up
1. Find each angle measure.
True or False. If false explain.
2. Every equilateral triangle is isosceles.
3. Every isosceles triangle is equilateral.
 Isosceles Triangle Theorem-If two sides of a triangle
are congruent, then the angles opposite those sides are
congruent.
 Since
, then:
∠A is congruent to ∠C
 The base is:
 The vertex angle is:
 The legs are:
 The base angles are:
Name the angles that must be
congruent.
Find the value of x in each isosceles
triangle.
If two angles of a triangle are congruent, then
the sides opposite those angles are congruent.
Name the sides that must be
congruent.
Find the value of x in each isosceles
triangle.
Find mF.
Find mG.
Find mH.
Find mN.
Find the value of x.
Find the value of y.
Find the value of JK.
Lesson Quiz
Find each angle measure.
1. mR
2. mP
Find each value.
3. x
5. x
4. y