Mock USAMO by probability1.01 dropped problems

Revision as of 15:46, 2 September 2006 by Me@home (talk | contribs) (Problem 2)

Problem 1

Solution

Problem 2

In triangle $ABC$, $AB \not= AC$, let the incircle touch $BC$, $CA$, and $AB$ at $D$, $E$, and $F$ respectively. Let $P$ be a point on $AD$ on the opposite side of $EF$ from $D$. If $EP$ and $AB$ meet at $M$, and $FP$ and $AC$ meet at $N$, prove that $MN$, $EF$, and $BC$ concur. Reason: The whole incircle business seemed rather artificial. Besides, it wasn’t that difficult.

Mock usamo.png

Solution

Problem 3

Solution

Problem 4

Solution

Problem 5

Solution

Problem 6

Solution