1. BELLWORK Given: 1 ≌ 2, BC ≌ DA Prove: EC ≌ EA B D C A E F 1 2
Given: A ≌ D, AB ≌ CD, AF ≌ ED
Prove: ∆FAC ≌ ∆EDB A B C D E F

2. Objective Vocabulary Base angles Vertex angle Base legs
Unit 4 – Triangle Congruence Isosceles and Equilateral Triangles
Objective
Use properties of isosceles and equilateral trianlges.
Vocabulary
Base angles
Vertex angle
Base
legs

3. Isosceles Triangle: At least 2 sides 
Unit 4 – Triangle Congruence Isosceles and Equilateral Triangles
Isosceles Triangle: At least 2 sides 
Angles opposite of legs are 
vertex angle
If I know
then I know
legs
base
base angles
If two angles are , then their opposite sides are also 
If I know
then I know

4. a y 6x 50° b 12 The perimeter = 30 10 x 40° s r The perimeter = 21
Unit 4 – Triangle Congruence Isosceles and Equilateral Triangles 6x
The perimeter = 30 12 y
50° a b x
The perimeter = 21 10
40° r s

5. Equilateral Triangle: three sides 
Unit 4 – Triangle Congruence Isosceles and Equilateral Triangles
Equilateral Triangle: three sides 
If equilateral then equiangular
If I know
then I know
If equiangular then equilateral
If I know
then I know

6. What are the values of each variable?
Unit 4 – Triangle Congruence Isosceles and Equilateral Triangles
What are the values of each variable? 6x 2x
3x-y
5x + 4 z
What is the perimeter?

7. CLASSWORK – match each problem with an answer
Unit 4 – Triangle Congruence Isosceles and Equilateral Triangles
CLASSWORK – match each problem with an answer 2. 2b
3b+5
50° c 3.
40° a 1.
Answers 5. 2y 4.

8. Unit 4 – Triangle Congruence 4.7 CPCTC
Given: Isosceles ∆PQR, base QR,
PA  PB
Prove: AR  BQ

9. Unit 4 – Triangle Congruence 4.9 Isosceles and Equilateral Triangles
Homework:
4.9(288): 15,16,19,28,29,33,34
14)33 16) 31 18)48 28)58,64,122 34)3