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Taiwan APMO Prelininary
2020 Taiwan APMO Preliminary
P1
2020 Taiwan APMO Preliminary Problem 1
2020 Taiwan APMO Preliminary Problem 1
Source: 2020 Taiwan APMO Preliminary
July 23, 2020
Taiwan
algebra
trigonometry
Problem Statement
Let
△
A
B
C
\triangle ABC
△
A
BC
satisfies
cos
A
:
cos
B
:
cos
C
=
1
:
1
:
2
\cos A:\cos B:\cos C=1:1:2
cos
A
:
cos
B
:
cos
C
=
1
:
1
:
2
, then
sin
A
=
t
\sin A=\sqrt{t}
sin
A
=
t
(
s
∈
N
,
t
∈
Q
+
s\in\mathbb{N},t\in\mathbb{Q^+}
s
∈
N
,
t
∈
Q
+
and
t
t
t
is an irreducible fraction). Find
s
+
t
s+t
s
+
t
.
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