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1996 USAMO Problems/Problem 5

Revision as of 09:49, 29 January 2013 by DVA6102 (talk | contribs)

Problem:

Let $ABC$ be a triangle, and $M$ an interior point such that $\angle MAB=10^\circ$, $\angle MBA=10^\circ$ , $\angle MAC= 40^\circ$ and $\angle MCA=30^\circ$. Prove that the triangle is isosceles.



Solution:

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