1.4 MEASURE AND CLASSIFY ANGLES

Mr. Saucedo

Milby High School

OBJECTIVE:

We will learn to name, measure and classify angles.

ANGLE

DEFINITION Two different rays with the same endpoint.

VISUAL

LABEL <ABC, < CBA or < B.

ANGLE IDENTIFICATION

ACUTE ANGLELess than 90 degrees

RIGHT ANGLEExactly 90 degrees.

OBTUSE ANGLEMore than 90 degrees but less than 180.

STRAIGHT ANGLEExactly 180 degres.

ACTIVITY

Use a protractor to draw the following angles.

1. m<ABC=135° 1. m<CDE= 40°

3. Right angle XYZ.

GUIDED EXAMPLE 1

Use the diagram to find the measure the indicated angle. Then classify the angle.

1. <AOD:2. <AOB3. <COE4. <BOF 5. <BOC

ANGLE ADDITION POSTULATE

GUIDED EXAMPLE 2

Given that m<AOB=45° and m<COB=30°, find m<COA.

GUIDED EXAMPLE 3

Given that m<ABC=101°, and m<DBA=38°, find m<CBD.

GUIDED EXAMPLE 4

m<1=(2x+10)°, and and m<2=(4x-3)°.Given that m<AXC=145°, find m<1, and m<2.

GUIDED EXAMPLE 4

Ray AB bisects <CAD. If m<CAB=18°, find m<CAD.

INDEPENDENT PRACTICE

Geometry book, pages 28-31.Problems: 6, 7, 8, 9, 10, 16, 18, 20, 22, 24, 26, 30, 34, 36,

38, 40

Pre-AP: add problem 50.

HOMEWORK:

Workbook, pages 10, 11 and 12. Problems: 4, 6, 8, 10, 12, 13, 14, 15, 16, 21,

Pre-AP: add problem 23.

SUBMIT HOMEWORK ON A SEPARATE SHEET OF PAPER. YOU DON’T HAVE TO WRITE OUT THE INSTRUCTIONS OR PROBLEMS, BUT SHOW YOUR WORK IF YOU WANT PARTIAL CREDIT.