MathDB
Problems
Contests
International Contests
Tuymaada Olympiad
1999 Tuymaada Olympiad
1
Tuymaada 1999, Q5
Tuymaada 1999, Q5
Source: Tuymaada 1999, Q5
July 31, 2012
geometry
geometric transformation
reflection
trigonometry
geometry unsolved
Problem Statement
In the triangle
A
B
C
ABC
A
BC
we have
∠
A
B
C
=
10
0
∘
\angle ABC=100^\circ
∠
A
BC
=
10
0
∘
,
∠
A
C
B
=
6
5
∘
\angle ACB=65^\circ
∠
A
CB
=
6
5
∘
,
M
∈
A
B
M\in AB
M
∈
A
B
,
N
∈
A
C
N\in AC
N
∈
A
C
, and
∠
M
C
B
=
5
5
∘
\angle MCB=55^\circ
∠
MCB
=
5
5
∘
,
∠
N
B
C
=
8
0
∘
\angle NBC=80^\circ
∠
NBC
=
8
0
∘
. Find
∠
N
M
C
\angle NMC
∠
NMC
.St.Petersburg folklore
Back to Problems
View on AoPS