P257
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Angular Bisectors

ℹ️Published on Saturday, 26th September 2009, 05:00 am; Solved by 787;
Difficulty rating: 85%

Given is an integer sided triangle $ABC$ with sides $a \le b \le c$. ($AB = c$, $BC = a$ and $AC = b$.)
The angular bisectors of the triangle intersect the sides at points $E$, $F$ and $G$ (see picture below).

0257_bisector.gif

The segments $EF$, $EG$ and $FG$ partition the triangle $ABC$ into four smaller triangles: $AEG$, $BFE$, $CGF$ and $EFG$.
It can be proven that for each of these four triangles the ratio area($ABC$)/area(subtriangle) is rational.
However, there exist triangles for which some or all of these ratios are integral.

How many triangles $ABC$ with perimeter $\le 100\,000\,000$ exist so that the ratio area($ABC$)/area($AEG$) is integral?



Soluzione

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