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1996 APMO
3
3
Part of
1996 APMO
Problems
(1)
ABCD cyclic --> incenters of BCD, etc. form rectangle
Source: Kedlaya; also: APMO 1996, Problem 3
1/23/2005
If
A
B
C
D
ABCD
A
BC
D
is a cyclic quadrilateral, then prove that the incenters of the triangles
A
B
C
ABC
A
BC
,
B
C
D
BCD
BC
D
,
C
D
A
CDA
C
D
A
,
D
A
B
DAB
D
A
B
are the vertices of a rectangle.
geometry
incenter
rectangle
cyclic quadrilateral
geometry proposed
Angle Chasing