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Saint Petersburg Mathematical Olympiad
2008 Saint Petersburg Mathematical Olympiad
3
St Petersburgh 2008 #3
St Petersburgh 2008 #3
Source:
July 23, 2011
geometry
angle bisector
geometry proposed
Problem Statement
Pentagon
A
B
C
D
E
ABCDE
A
BC
D
E
has circle
S
S
S
inscribed into it. Side
B
C
BC
BC
is tangent to
S
S
S
at point
K
K
K
. If
A
B
=
B
C
=
C
D
AB=BC=CD
A
B
=
BC
=
C
D
, prove that angle
E
K
B
EKB
E
K
B
is a right angle.
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