geometry
posted by Aaa .
Let the incircle of triangle $ABC$ be tangent to sides $\overline{BC}$, $\overline{AC}$, and $\overline{AB}$ at $D$, $E$, and $F$, respectively. Prove that triangle $DEF$ is acute.
I have tried proving that triangle DEF's angles were les than the opposite angles in triangle ABC, but that wasn't really complete. Can anyone help?

Geometry (?) 
PsyDAG
What do all the dollar signs ($) signify?

geometry 
Atticus Finch
They're just a format you can ignore them

geometry 
AoPS
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