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Putnam
1965 Putnam
B6
B6
Part of
1965 Putnam
Problems
(1)
Putnam 1965 B6
Source:
9/28/2020
If
A
A
A
,
B
B
B
,
C
C
C
,
D
D
D
are four distinct points such that every circle through
A
A
A
and
B
B
B
intersects (or coincides with) every circle through
C
C
C
and
D
D
D
, prove that the four points are either collinear (all on one line) or concyclic (all on one circle).
Putnam