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Federal Math Competition of Serbia and Montenegro
2006 Federal Math Competition of S&M
Problem 1
find angle in quadrilateral (Serbia MO 2006 1st Grade P1)
find angle in quadrilateral (Serbia MO 2006 1st Grade P1)
Source:
April 10, 2021
geometry
quadrilateral
Problem Statement
In a convex quadrilateral
A
B
C
D
ABCD
A
BC
D
,
∠
B
A
C
=
∠
D
A
C
=
5
5
∘
\angle BAC=\angle DAC=55^\circ
∠
B
A
C
=
∠
D
A
C
=
5
5
∘
,
∠
D
C
A
=
2
0
∘
\angle DCA=20^\circ
∠
D
C
A
=
2
0
∘
, and
∠
B
C
A
=
1
5
∘
\angle BCA=15^\circ
∠
BC
A
=
1
5
∘
. Find the measure of
∠
D
B
A
\angle DBA
∠
D
B
A
.
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