SOLUTION: Evaluate: 2cos^2(7pi/12) - 1
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Question 1029655: Evaluate: 2cos^2(7pi/12) - 1
Answer by fractalier(6550) (Show Source): You can put this solution on YOUR website!
For this one we can use the identity:
but we'll go backwards...thus
2cos^2(7pi/12) - 1 = cos(2*(7pi/12)) = cos(7pi/6) = -cos(pi/6) =
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