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RS = \sqrt2 SQ if AD=CR , CR _|_ AB, ABC right isosceles

Source: Indonesia INAMO Shortlist 2008 G2

August 25, 2021
isoscelesequal segmentsgeometry

Problem Statement

Let ABCABC be an isosceles triangle right at CC and PP any point on CBCB. Let also QQ be the midpoint of ABAB and R,SR, S be the points on APAP such that CRCR is perpendicular to APAP and AS=CR|AS|=|CR|. Prove that the RS=2SQ|RS| = \sqrt2 |SQ|.