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Easy Trigonometric Inequality - ILL 1970 - Problem 10.
Easy Trigonometric Inequality - ILL 1970 - Problem 10.
Source:
May 24, 2011
inequalities
trigonometry
Problem Statement
In
△
A
B
C
\triangle ABC
△
A
BC
, prove that
1
<
∑
c
y
c
cos
A
≤
3
2
1< \sum_{cyc}{\cos A}\le \frac{3}{2}
1
<
∑
cyc
cos
A
≤
2
3
.
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