MathDB
JBMO 2012 Problem 2

Source: JBMO 2012

June 27, 2012
geometryJBMO

Problem Statement

Let the circles k1k_1 and k2k_2 intersect at two points AA and BB, and let tt be a common tangent of k1k_1 and k2k_2 that touches k1k_1 and k2k_2 at MM and NN respectively. If tAMt\perp AM and MN=2AMMN=2AM, evaluate the angle NMBNMB.