Online Geometry Problems

Geometry Problem 84. Contact Triangles Areas, Incircle, Excircle, Inradius, Exradius. High School, College, Math Education

In the figure below, given a triangle ABC, the incircle of radius r and the contact triangle of area S1, the excircle of radius ra and the contact triangle of area Sa. Prove that: \(\dfrac{S_1}{S_a}=\dfrac{r}{r_a}\).

Geometry problem about triangle, incircle, excircle, contact triangles area



1. See Problems 81, 82, 83.

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