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Mathematics
Mathematics
Problem
In parallelogram
A
B
C
D
ABCD
A
B
C
D
, the diagonals
A
C
AC
A
C
and
B
D
BD
B
D
intersect at
O
O
O
. Prove that the four triangles
△
A
O
B
\triangle AOB
△
A
O
B
,
△
B
O
C
\triangle BOC
△
B
O
C
,
△
C
O
D
\triangle COD
△
C
O
D
and
△
D
O
A
\triangle DOA
△
D
O
A
are equal in area.
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