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projections distance on angle bisectors equals to inradius

Source: 2018 Oral Moscow Geometry Olympiad grades 10-11 p1

July 25, 2019
right trianglegeometryinradiusprojections

Problem Statement

In a right triangle ABCABC with a right angle CC, let AKAK and BNBN be the angle bisectors. Let D,ED,E be the projections of CC on AK,BNAK, BN respectively. Prove that the length of the segment DEDE is equal to the radius of the inscribed circle.