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Switzerland Contests
Swiss NMO - geometry
2021.8
2021.8
Part of
Swiss NMO - geometry
Problems
(1)
Geometry from YouTube
Source: Switzerland Final Round 2021 P8
2/24/2021
Let
△
A
B
C
\triangle ABC
△
A
BC
be a triangle with
A
B
=
A
C
AB =AC
A
B
=
A
C
and
∠
B
A
C
=
2
0
∘
\angle BAC = 20^{\circ}
∠
B
A
C
=
2
0
∘
. Let
D
D
D
be point on the side
A
B
AB
A
B
such that
∠
B
C
D
=
7
0
∘
\angle BCD = 70^{\circ}
∠
BC
D
=
7
0
∘
. Let
E
E
E
be point on the side
A
C
AC
A
C
such that
∠
C
B
E
=
6
0
∘
\angle CBE = 60^{\circ}
∠
CBE
=
6
0
∘
. Determine the value of angle
∠
C
D
E
\angle CDE
∠
C
D
E
.
geometry