M217 Section 1.3

9
M217 Section 1.3 Measuring Angles

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M217 Section 1.3. Measuring Angles. Angle Terminology:. C. I. Angle : 2 different rays with the same endpoint Vertex : Common endpoint - A Sides : Two rays – Naming: Interior: Exterior: On:. 2. A. B. E. Angle Measures, Congruency. - PowerPoint PPT Presentation

Transcript of M217 Section 1.3

Page 1: M217  Section 1.3

M217 Section 1.3

Measuring Angles

Page 2: M217  Section 1.3

Angle Terminology:• Angle: 2 different rays with the

same endpoint• Vertex: Common endpoint - A• Sides: Two rays –• Naming:• Interior:• Exterior:• On:

AB and AC

C

A B

E

I2

Page 3: M217  Section 1.3

Angle Measures, Congruency• Angles are measured using a protractor• If two angles have the same measure, then they are

congruent angles and are marked with arcs• the

A

B

CD

E

F

measure of angle A: m A

Page 4: M217  Section 1.3

4

Classifying Angles by Measure

Term Definition ExampleAcute

Right

ObtuseStraight

Page 5: M217  Section 1.3

Angle Addition Postulate

m PST

m RSP

S T

P

R• If P is on the interior of angle RST, then

• Basically: two parts = 1 whole

m RSP m PST m RST

Page 6: M217  Section 1.3

T is on the interior of angle PQR1. 25

11Find

m PQRm RQTm PQT

2. (10 7)(5 )(4 6)

Find and

m PQR xm RQT xm PQT xx m PQR

Page 7: M217  Section 1.3

Defn: Angle Bisector• An Angle Bisector is a ray that divides an

angle into two congruent angles

Page 8: M217  Section 1.3

Angle Bisector3. bisects

(10 13)(6 1)

Find , and

QT PQRm RQT xm PQT xx m PQT m PQR

4. bisects (5 3)(12 4)

Find and

QT PQRm PQT ym PQR yy m TQR

Page 9: M217  Section 1.3

Reading a Protractor• Notice two sets of

numbers

• Now try #4 – 6 on page 24. Then begin HW

4. 15◦, acute

5. 105 ◦, obtuse

6. 110 ◦, obtuse