1. 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?
b.) Using CPCTC name all the other corresponding parts that are congruent.
R Z
P Q X Y

2. Section 4.8: Isosceles and Equilateral Triangles
Geometry
Section 4.8: Isosceles and Equilateral Triangles
Objective: SWBAT use theorems about isosceles and equilateral triangles.

3. Isosceles Triangle
Isosceles Triangles have two congruent sides and two congruent base angles across from the congruent sides. A
B and C are the base
angles that are
congruent because
they are across from
the congruent sides
AC and AB.
B C

4. 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

5. Solve for the variable(s) and the ?
1.) ) )

6. Solve for the variable(s).
4.) ) )

7. 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
20.) 60 ft.
21.) 50 in.
22.) 69 m.
23.) 22 yd., x=42, y=69
24.) 1. given
17.) 25 ft.
18.) 28 in.
19.) 33 m.

9. Homework
Page 267 – 277
#11-13
#15-17
#19-25 odds