Download Section 4.8: Isosceles and Equilateral Triangles

Warm Up
1.) What does CPCTC stand for?
2.) What does CPCTC mean in your own words?
3.) a.) Why are the two triangles below
congruent?
R
P
Z
Q
X
Y
b.) Using CPCTC name all the other
corresponding parts that are congruent.
Geometry
Section 4.8: Isosceles and Equilateral
Triangles
Objective:
SWBAT use theorems about isosceles and
equilateral triangles.
Isosceles Triangle
Isosceles Triangles have two congruent sides
and two congruent base angles across from
the congruent sides.
A
B
C
B and C are the base
angles that are
congruent because
they are across from
the congruent sides
AC and AB.
Equilateral Triangle
Equilateral Triangles have all three sides
congruent to each other, so all three angles will
also be congruent to each other. This makes all
equilateral triangles also equiangular.
A
Angles A, B, and C are
congruent because
they are across from
the congruent sides
AC, CB, and AB.
B
C
Solve for the variable(s) and the ?
1.)
2.)
3.)
Solve for the variable(s).
4.)
5.)
6.)
Solve for the variable(s).
7.)
8.)
Class work: w/s 4.8 A:
skip #’s 5, 6, 8, 9, 11, 13, 14, 16
Answers:
1.) EAC, ECA
2.) DA, DE
3.) BF, DF, BD
4.) ABC, BAC, BCA
7.) 18
10.) 3
12.) 8
15.) x = 15, y = 8
17.) 25 ft.
18.) 28 in.
19.) 33 m.
20.) 60 ft.
21.) 50 in.
22.) 69 m.
23.) 22 yd., x=42, y=69
24.) 1. given
Homework
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