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2006 Romanian NMO Problems/Grade 9/Problem 2

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Problem

Let \displaystyle ABC and \displaystyle DBC be isosceles triangles with the base \displaystyle BC. We know that \displaystyle \angle ABD = \frac{\pi}{2}. Let \displaystyle M be the midpoint of \displaystyle BC. The points \displaystyle E,F,P are chosen such that \displaystyle E \in (AB), \displaystyle P \in (MC), \displaystyle C \in (AF), and \displaystyle \angle BDE = \angle ADP = \angle CDF. Prove that \displaystyle P is the midpoint of \displaystyle EF and \displaystyle DP \perp EF.

Solution

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See also

Want to learn how to tackle those tough MATHCOUNTS and AMC counting and probability problems? Check out Art of Problem Solving's Introduction to Counting & Probability by David Patrick.
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