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National and Regional Contests
Cuba Contests
Cuba MO
2009 Cuba MO
8
8
Part of
2009 Cuba MO
Problems
(1)
80-80-20 classic problem, AD = BC
Source: 2009 Cuba 2.8
8/27/2024
Let
A
B
C
ABC
A
BC
be an isosceles triangle with base
B
C
BC
BC
and
∠
B
A
C
=
2
0
o
\angle BAC = 20^o
∠
B
A
C
=
2
0
o
. Let
D
D
D
a point on side
A
B
AB
A
B
such that
A
D
=
B
C
AD = BC
A
D
=
BC
. Determine
∠
D
C
A
\angle DCA
∠
D
C
A
.
geometry
angles
isosceles