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India Contests
Regional Mathematical Olympiad
2001 India Regional Mathematical Olympiad
5
5
Part of
2001 India Regional Mathematical Olympiad
Problems
(1)
Prove an angle
Source: Indian RMO 2001 Problem5
10/27/2005
In a triangle
A
B
C
ABC
A
BC
,
D
D
D
is a point on
B
C
BC
BC
such that
A
D
AD
A
D
is the internal bisector of
∠
A
\angle A
∠
A
. Suppose
∠
B
=
2
∠
C
\angle B = 2 \angle C
∠
B
=
2∠
C
and
C
D
=
A
B
CD =AB
C
D
=
A
B
. prove that
∠
A
=
7
2
∘
\angle A = 72^{\circ}
∠
A
=
7
2
∘
.
geometry
circumcircle
trigonometry
congruent triangles