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National and Regional Contests
Vietnam Contests
Vietnam National Olympiad
1966 Vietnam National Olympiad
2
2
Part of
1966 Vietnam National Olympiad
Problems
(1)
VietNam MO 1966-Pr.2
Source:
2/18/2007
a
,
b
a, b
a
,
b
are two fixed lines through
O
O
O
. Variable lines
x
,
y
x, y
x
,
y
are parallel.
x
x
x
intersects a at
A
A
A
and
b
b
b
at
C
C
C
,
y
y
y
intersects
a
a
a
at
B
B
B
and
b
b
b
at
D
D
D
. The lines
A
D
AD
A
D
and
B
C
BC
BC
meet at
M
M
M
. The line through
M
M
M
parallel to
x
x
x
meets
a
a
a
at
L
L
L
and
b
b
b
at
N
N
N
. What can you say about
L
,
M
,
N
L, M, N
L
,
M
,
N
? Find the locus
M
M
M
.
geometry open
geometry