MathDB
Right Triangle and Circles

Source:

December 28, 2006
geometryinradiusincenteranalytic geometrysimilar triangles

Problem Statement

Let PQR\triangle{PQR} be a right triangle with PQ=90PQ=90, PR=120PR=120, and QR=150QR=150. Let C1C_{1} be the inscribed circle. Construct ST\overline{ST} with SS on PR\overline{PR} and TT on QR\overline{QR}, such that ST\overline{ST} is perpendicular to PR\overline{PR} and tangent to C1C_{1}. Construct UV\overline{UV} with UU on PQ\overline{PQ} and VV on QR\overline{QR} such that UV\overline{UV} is perpendicular to PQ\overline{PQ} and tangent to C1C_{1}. Let C2C_{2} be the inscribed circle of RST\triangle{RST} and C3C_{3} the inscribed circle of QUV\triangle{QUV}. The distance between the centers of C2C_{2} and C3C_{3} can be written as 10n\sqrt{10n}. What is nn?