MEMO 2008 pojedinačno problem 3
Dodao/la:
arhivaApril 28, 2012 Let
![ABC](/media/m/a/c/7/ac75dca5ddb22ad70f492e2e0a153f95.png)
be an isosceles triangle with
![AC = BC](/media/m/0/3/d/03d754578decf579d9b455ade027f761.png)
. Its incircle touches
![AB](/media/m/5/2/9/5298bd9e7bc202ac21c423e51da3758e.png)
in
![D](/media/m/7/0/0/7006c4b57335ab717f8f20960577a9ef.png)
and
![BC](/media/m/5/0/0/5005d4d5eac1b420fbabb76c83fc63ad.png)
in
![E](/media/m/8/b/0/8b01e755d2253cb9a52f9e451d89ec11.png)
. A line distinct of
![AE](/media/m/c/e/3/ce31f42a92358c211bccb23e6a92fb55.png)
goes through
![A](/media/m/5/a/e/5ae81275ee67d638485e903bdc0e9cde.png)
and intersects the incircle in
![F](/media/m/3/e/8/3e8bad5df716d332365fca76f53c1743.png)
and
![G](/media/m/f/e/b/feb7f8fc95cee3c3a479382202e06a86.png)
. Line
![AB](/media/m/5/2/9/5298bd9e7bc202ac21c423e51da3758e.png)
intersects line
![EF](/media/m/f/5/5/f5594d5ec47ea777267cf010e788fedd.png)
and
![EG](/media/m/a/b/5/ab55e009d6dc385fd617dc2306f27e89.png)
in
![K](/media/m/e/1/e/e1ed1943d69f4d6a840e99c7bd199930.png)
and
![L](/media/m/f/c/1/fc1ae4eb78da7d1352cbf1f8217ab286.png)
, respectively. Prove that
![DK = DL](/media/m/b/7/1/b7108317a06911e10d45518c844a3df7.png)
.
%V0
Let $ABC$ be an isosceles triangle with $AC = BC$. Its incircle touches $AB$ in $D$ and $BC$ in $E$. A line distinct of $AE$ goes through $A$ and intersects the incircle in $F$ and $G$. Line $AB$ intersects line $EF$ and $EG$ in $K$ and $L$, respectively. Prove that $DK = DL$.
Source: Srednjoeuropska matematička olimpijada 2008, pojedinačno natjecanje, problem 3