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National and Regional Contests
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(China) National High School Mathematics League
2017 China Second Round Olympiad
2
China Second Round Olympiad 2017 Test 1 Q2
China Second Round Olympiad 2017 Test 1 Q2
Source: Sep 10, 2017
September 10, 2017
algebra
inequalities
Problem Statement
Let
x
,
y
x,y
x
,
y
are real numbers such that
x
2
+
2
c
o
s
y
=
1
x^2+2cosy=1
x
2
+
2
cosy
=
1
. Find the ranges of
x
ā
c
o
s
y
x-cosy
x
ā
cosy
.
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