A Theorem about Two Tangent Circles

blue circle radius

slope(AB)

≈

3.13

slope(DC)

≈

3.13

Let A and C be the centers of two tangent circles. Draw a line from a point E through the intersection of the two circles and let that line intersect the circles at B and D. Then AB is parallel to CD.

Details

For more information see Two Touching Circles.

External Links

Parallel (Wolfram MathWorld)

Tangent Circles (Wolfram MathWorld)

Permanent Citation

Jay Warendorff

"A Theorem about Two Tangent Circles"
http://demonstrations.wolfram.com/ATheoremAboutTwoTangentCircles/
Wolfram Demonstrations Project
Published: March 7, 2011