Angles MeasuresAngles Measures

Objective:Objective:

Identify angles & parts Identify angles & parts of anglesof anglesUse the angle addition Use the angle addition postulate to find the postulate to find the measures of anglesmeasures of angles

RAYSRAYS A ray is a segment that is extended indefinitely in one direction.A ray is a segment that is extended indefinitely in one direction. Rays have only one endpoint and that point is always named first Rays have only one endpoint and that point is always named first

when naming the ray.when naming the ray.

Ray PQ , written PQ , consists of the points on PQ and all points S on Ray PQ , written PQ , consists of the points on PQ and all points S on PQ such that Q is between P & S.PQ such that Q is between P & S.

P Q S

AnglesAngles It is formed by 2 non-collinear rays called the It is formed by 2 non-collinear rays called the sides sides

of the angleof the angle and common end point called and common end point called vertex.vertex.

Z

X

Y1

The sides are: YX and YZ and the vertex Y

How we name the angle?

Y XYZ ZYX 1

AnglesAngles

S P

Q

R

1

2

3

What number names ?QSP

2What is the vertex of ?

What are the sides of ?1

AnglesAngles

A

B

C

D

Interior

Exterior

AnglesAngles

Measure of an angle.

To measure an angle we need to use the protractor

How we use the protractor

AnglesAngles

To measure an angle place the center of the protractor over the vertex of the angle.

Align the mark labeled 0 on either side of the scale with one side of the angle

y

z

x

AnglesAngles

Find the degree measure of each numbered angle.

2 13

4

m = ?

1

m = ?

2

m = ?

3

m = ?

4

30

95

18

37

AnglesAngles

R

S

P

Q

If R is in the interior of , then m + m = m

If m + m = m then R is in the interior of .

PQS PQR RQS PQS

PQSPQR RQS PQS