This is the "10.1: Tangents to Circles" page of the "Geometry Chapter 10" guide.
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Geometry Chapter 10   Tags: geometry, mahlman, math  

Last Updated: Feb 19, 2014 URL: Print Guide RSS Updates

10.1: Tangents to Circles Print Page



If a line is tangent to a circle, it is perpendicular to the radius drawn to the point of tangency.

Common Tangents:

Common tangents are lines or segments that are tangent to more than one circle at the same time.

4 Common Tangents
(2 completely separate circles)

2 external tangents (blue)
2 internal tangents (black)

3 Common Tangents
(2 externally tangent circles)

2 external tangents (blue)
1 internal tangent (black)


1 Common Tangent
(2 internally tangent circles)

1 external tangent (blue)
0 internal tangents

0 Common Tangents

(2 concentric circles)
Concentric circles are circles
with the same center.

0 external tangents
0 internal tangents


Tangent to Circles


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