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Iran National Math Olympiad-Day 1-Problem 3

Source:

April 30, 2010
geometrygeometric transformation

Problem Statement

Circles W1,W2W_1,W_2 meet at DDand PP. AA and BB are on W1,W2W_1,W_2 respectively, such that ABAB is tangent to W1W_1 and W2W_2. Suppose DD is closer than PP to the line ABAB. ADAD meet circle W2W_2 for second time at CC. Let MM be the midpoint of BCBC. Prove that DPM=BDC\angle{DPM}=\angle{BDC}.