very easy!
Source: ?
January 20, 2015
geometrycircumcircleslopepower of a pointradical axisIran
Problem Statement
ABC is a triangle with A=90 and C=30.Let M be the midpoint of BC. Let W be a circle passing through A tangent in M to BC. Let P be the circumcircle of ABC. W is intersecting AC in N and P in M. prove that MN is perpendicular to BC.