Three Mutually Tangent Circles, Collinear Centers, and Curvilinear Incircle Radii Relations


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Target Audience: K-12, Honors Geometry, and College Mathematics Education.

In Problem 1627, we explore three mutually tangent circles with collinear centers and a common external tangent line. The challenge is to prove using synthetic similarity that the radii satisfy a geometric progression, and to establish the elegant radical and harmonic difference relations involving the radii of their curvilinear inscribed circles.
Explore the full theorem and illustrated diagram by clicking the image below.


Illustration of Geometry Problem 1627: Three Mutually Tangent Circles and Collinear Centers


Click for additional details and full diagram.

How to contribute:
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