11/18/09Do Now Have your homework out on your desk. Find all of the angle measures below.

<1

100°80°(x+5)°

70°(x-5)°

<4

11/18/09 Do Now Find all of the angle measures below.

<1

100°80°(x+5)°

70°(x-5)°

<4

<1 + 70° = 100°<1 = 30°

11/18/09 Do Now Find all of the angle measures below.

<1

100°80°(x+5)°

70°(x-5)°

<4

(x-5)° + (x+5)° = 80°x + x - 5 + 5 = 802x = 80x = 40

11/18/09 Do Now Find all of the angle measures below.

<1

100°80°(45)°

70°(40-5)° = 35°

<4

100° + 45° + <4 = 180°145° + <4 = 180°<4 = 35°

Homework Answers Side B#13)<1 = 36

<2 = 122

<3 = 122

<4 = 38

#14)<1 = 50

<2 = 90

<3 = 60

<4 = 60

<5 = 60

<6 = 60

<7 = 110

#15)<A = 60

<B = 30

<C = 90

#16)<A = 83

<B = 38

<C = 59

#17)<A = 40

<B = 50

<C = 90

Homework Answers Side C#8)<1 = 75

<2 = 55

<3 = 55

<4 = 40

<5 = 140

<6 = 40

<7 = 75

<8 = 65

<9 = 115

#9)<1 = 30

<2 = 60

<3 = 50

<4 = 35

<5 = 90

<6 = 55

<7 = 55

<8 = 125

<9 = 35

#10)<A = 30

<B = 60

<C = 90

#11)<A = 64

<B = 67

<C = 49

#12)<A = 100

<B = 50

<C = 30

#13) 131

#14) 100

#15) 125

4-7: Isosceles Triangles

Objective: Use properties of Isosceles Triangles

Angles of an Isosceles Triangle

Base Angles Theorem - The base angles of an isosceles triangle are congruent.

CB

A

Generalization:

Congruent angles within a triangles are opposite congruent sides of a triangle.

The converse is also true.

Ex. 1: Solve for x and y.

x°

58°

y°

F

E

D

Ex. 2: Solve for x.

2x + 10°

7x - 5°

F

E

D

Ex. 3: Solve for x and y.

D

L

I

EF

y°

x°

70°

Homework

WS 1 – 6 (Both Sides)