CK-12 Geometry-Concepts

http://www.ck12.org Chapter 1. Basics of Geometry

1.5 Angle Measurement

Here you’ll learn how to measure an angle with a protractor and how to apply the Angle Addition Postulate to find
unknown values.

What if you needed a way to describe the size of an angle? After completing this Concept, you’ll be able to use a
protractor to measure an angle in degrees.

Watch This

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/52598

CK-12 Foundation: Chapter1MeasuringAnglesA

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/1269

James Sousa: Animation of Measuring Angles with a Protractor

Watch the first part of this video.

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/1270

James Sousa: Angle Basics

Guidance

We measure a line segment’slengthwith a ruler. Angles are measured with something called aprotractor. A
protractor is a measuring device that measures how “open” an angle is. Angles are measured in degrees, and labeled
with a◦symbol.