Geometry Problem 1099: Four Circles, Common External Tangent, Common Internal Tangent, Radius, Measurement, Sangaku, Typography, iPad Apps

Proposition

The figure below shows the circles O1 (radius r1) and O2 (radius r2). A1A2 and B1B2 are the common external tangents and CD is a common internal tangent. Circle O3 (radius r3) touches A1C, CD, and circle O1. Circle O4 (radius r4) touches B1D, CD, and circle O1. Prove that Formula to prove.


Art and Typography of Geometry Problem 1099: Four Circles, Common External Tangent, Common Internal Tangent, Radius, Measurement, Sangaku, iPad Apps


Geometric Art using Mobile Apps

Geometric art is a form of art based on the use and application of geometric figures. A geometric figure is any set or combination of points, lines, surfaces and solids.

A mobile app or mobile application software is a computer program designed to run on smartphones and tablet computers.

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Original problem 1099.

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