CK-12 Geometry-Concepts

9.2. Tangent Lines http://www.ck12.org

9.2 Tangent Lines

Here you’ll learn two theorems about tangent lines and how to apply them.

What if a line were drawn outside a circle that appeared to touch the circle at only one point? How could you
determine if that line were actually a tangent? After completing this Concept, you’ll be able to apply theorems to
solve tangent problems like this one.

Watch This

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/52418

CK-12 Foundation: Chapter9TangentLinesA

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/1326

James Sousa: Tangent Lines to a Circle

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/1327

James Sousa: Tangent Lines to a Circle Example Problems

Guidance

The tangent line and the radius drawn to the point of tangency have a unique relationship. Let’s investigate it here.

Investigation: Tangent Line and Radius Property

Tools needed: compass, ruler, pencil, paper, protractor