Angles

MEAP REVIEW

Vocabulary

• An angle has two sides and a vertex.

• The sides of the angles are rays. The rays share a common endpoint (the vertex)

• Angles are measured in units called degrees.

Types of Angles

When lines intersect to form right angles, then they are classified as perpendicular lines.

ProtractorA device used to measure angles.

Reading a ProtractorDate: 9/8/96 at 22:29:58 From: Bob Vanselow Subject: Reading a Protractor Which side of a protractor scale do you use?

Date: 9/9/96 at 11:39:23 From: Doctor Robert Subject: Re: Reading a Protractor I think that the easiest way to decide which scale to use is to look at the angle you're measuring. If it is greater than a right angle (more than ninety degrees) then use the scale that has numbers greater than 90. If the angle is obviously acute (measures less than 90 degrees), use the scale which has numbersless than 90. Of course you have to line up the protractor correctly with the center point on the vertex of the angle and one of the rays of the anglecoincide with the line on the protractor. Happy measuring! -Doctor Robert, The Math Forum Check out our web site! http://mathforum.org/dr.math/

Measuring Angles

• Place the center point of the protractor on the vertex of the angle and turn the protractor so that one side lines up with 0 on the inner scale.

Measuring Angles (strategy 2)

• Place the center point of the protractor on the vertex of the angle. Note where both rays cross the protractor. Subtract the two numbers (from the same scale)

Homework Time

Go to the Math Playground to use this interactive tool to measure angles.

Complete MEAP Review Angle Measurement Handout