Difference between revisions of "1963 IMO Problems/Problem 5"
(New page: ==Problem== Prove that <math>\cos{\frac{\pi}{7}}-\cos{\frac{2\pi}{7}}+\cos{\frac{3\pi}{7}}=\frac{1}{2}</math>. ==Solution== {{solution}} ==See Also== {{IMO box|year=1963|num-b=4|num-a=6...) |
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