SOLUTION: use double angle identity to find exact value of 2cos^2(75 degrees)-1

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Question 932139: use double angle identity to find exact value of 2cos^2(75 degrees)-1
Answer by lwsshak3(11628) About Me  (Show Source):
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use double angle identity to find exact value of 2cos^2(75 degrees)-1
2(cos^2(75))-1
2(1-sin^2(75)-1
2-2sin^2(75)-1
1-2sin^2(75)=cos(150)=-√3/2 (In quadrant II where cos<0)