Notes 1.4

Warm Up-9/17/09 #3

• Find the coordinate of the midpoint of AB if the coordinate of A is 7 and the coordinate of B is 201. Draw a diagram for credit!

1.4 Angles

Obj: Use AAP and the definition of angle bisector to find angle measures.

Angle

• Formed by two rays or segments with the same endpoint

• Notation: Side

Side

Vertex

F

G

E

Naming an Angle:

• 1. Use three points– Vertex must be the middle

• 2. Use vertex

• 3. Use a numberSide

Side

Vertex

F

G

E

1

Example 1

• Name each angle in every way possible.

21

B

A

C

D

Classifying Angles• Acute

– measure between 0 and 90• Right

– measure of 90• Obtuse

– Measure between 90 and 180• Straight

– measure of 180Angle

Adjacent Angles

• Angles with a common vertex and a common side, but no common interior points

• Adjacent

Angle Addition PostulateAAP

•mAOB + mBOC = mAOCB

A

O

C

AND….

• mDOE + mEOF = 180

D F

E

O

Congruent Angles• Two angles with equal measures

• Notation: m1 = m2• Or: 1 2

• How to mark the diagram:• More than one pair of angles?

1

2

Angle Bisector

• Ray or segment that divides an angle into two congruent adjacent angles

3030

Example 2

• Segment AL bisects KAT. Find x. • m1 = 7x +3• m2 = 6x + 7

321

S T

K

L

A

Example 3

• m1 = x, m3 = 4x. Find x.

321

S T

K

L

A

Homework…

• Pages 21-22• 1-22, 26, 29, 31, 33 • Written Exercises