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International Contests
Tournament Of Towns
1991 Tournament Of Towns
(286) 2
(286) 2
Part of
1991 Tournament Of Towns
Problems
(1)
TOT 286 1991 Spring A J2 peprendicular in tangential pentagon
Source:
6/9/2024
The pentagon
A
B
C
D
E
ABCDE
A
BC
D
E
has an inscribed circle and the diagonals
A
D
AD
A
D
and
C
E
CE
CE
intersect in its centre
O
O
O
. Prove that the segment
B
O
BO
BO
and the side
D
E
DE
D
E
are perpendicular.(Folklore)
geometry
pentagon
perpendicular