SOLUTION: Simplify the expression by using a double-angle formula. cos^2(2pi/5)-sin^2(2pi/5)

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Question 1036271: Simplify the expression by using a double-angle formula.
cos^2(2pi/5)-sin^2(2pi/5)
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
cos^2(2pi/5)-sin^2(2pi/5) = cos(4pi/5)