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2005 JBMO Shortlist
7
6 points in a parallelogram, two equal segments
6 points in a parallelogram, two equal segments
Source: JBMO Shortlist 2005
October 13, 2017
geometry
parallelogram
JBMO
Problem Statement
Let
A
B
C
D
ABCD
A
BC
D
be a parallelogram.
P
∈
(
C
D
)
,
Q
∈
(
A
B
)
P \in (CD), Q \in (AB)
P
∈
(
C
D
)
,
Q
∈
(
A
B
)
,
M
=
A
P
∩
D
Q
M= AP \cap DQ
M
=
A
P
∩
D
Q
,
N
=
B
P
∩
C
Q
N=BP \cap CQ
N
=
BP
∩
CQ
,
K
=
M
N
∩
A
D
K=MN \cap AD
K
=
MN
∩
A
D
,
L
=
M
N
∩
B
C
L= MN \cap BC
L
=
MN
∩
BC
. Prove that
B
L
=
D
K
BL=DK
B
L
=
DK
.
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