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International Contests
IMO Longlists
1989 IMO Longlists
99
99
Part of
1989 IMO Longlists
Problems
(1)
A trisects BC
Source: IMO Longlist 1989, Problem 99
9/18/2008
Let
A
B
C
ABC
A
BC
be an equilateral triangle and
Γ
\Gamma
Γ
the semicircle drawn exteriorly to the triangle, having
B
C
BC
BC
as diameter. Show that if a line passing through
A
A
A
trisects
B
C
,
BC,
BC
,
it also trisects the arc
Γ
.
\Gamma.
Γ.
geometry unsolved
geometry