# 4 7 Use Isosceles and Equilateral Triangles by 8npcq3Pa

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```									4.7 Use Isosceles and
Equilateral Triangles
Notetaking Guide pages 108 – 110
5 4
Vocabulary
   The _______ of an isosceles triangle are the
legs
two congruent sides.
   The ____________ of an isosceles triangle is
vertex angle
the angle formed by the legs.
   The ______ of an isosceles triangle is the side
base
that is not the leg.
   The _____________ of an isosceles triangle
base angles
are the two angles adjacent to the base.
What does it look like?
<C
AC
Converse of The Isosceles Triangle
Theorem
   If two angles of a
triangle are
congruent, then
the sides
opposite those
angles are
congruent.
F   G
equiangular

equilateral
Reminder
   Each angle of an equilateral triangle
measures 60 degrees.

   The sum of the measures of the angles of a
triangle is 180 .
Example 2 Find measures in a triangle

equilateral

equiangular
180
60
60
Example 3 Use isosceles and equilateral
triangles

equiangular
equilateral
JL              8
<LJM
LJ
8
JL
8                    8
4
Example 4 Solve a multi-step problem

<DCA
equiangular          Corollary to the
Converse of Base Angles Theorem

<ACB
AAS Congruence Theorem
Checkpoint

H; J

15
Use parts (a) and (b) in Example 4 to
     DCA is equiangular
   3(m<CAD) = 180       Triangle Sum Theorem
     m<CAD = 60          Division Property

   Because      DCA is equiangular and
   You know that m<BAC = 60

        = 60 + 60
        = 120
Find the value of x.
x

62

x = 56
Find the value of x.

x = 7.5

10

6

2x - 5
Summary

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