MathDB
Problems
Contests
International Contests
IMO Longlists
1986 IMO Longlists
9
Prove that AD + DB = BC
Prove that AD + DB = BC
Source:
August 28, 2010
geometry unsolved
geometry
Problem Statement
In a triangle
A
B
C
ABC
A
BC
,
∠
B
A
C
=
10
0
∘
,
A
B
=
A
C
\angle BAC = 100^{\circ}, AB = AC
∠
B
A
C
=
10
0
∘
,
A
B
=
A
C
. A point
D
D
D
is chosen on the side
A
C
AC
A
C
such that
∠
A
B
D
=
∠
C
B
D
\angle ABD = \angle CBD
∠
A
B
D
=
∠
CB
D
. Prove that
A
D
+
D
B
=
B
C
.
AD + DB = BC.
A
D
+
D
B
=
BC
.
Back to Problems
View on AoPS