SOLUTION: cos^2 π/8 + cos^2 3π/8 +cos^2 5π/8 + cos^2 7π/8

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Question 1075809: cos^2 π/8 + cos^2 3π/8 +cos^2 5π/8 + cos^2 7π/8
Answer by ikleyn(52794)   (Show Source): You can put this solution on YOUR website!
.
1.     = .    Obviously.

      = .    Obviously.


2.    = .

     See the lesson  Trigonometric functions of half argument - Examples  in this site.


3.    =     ( Obviouly )

                        = 

     See the lesson  Trigonometric functions of half argument - Examples  in this site.


4.   Now you are armed / prepared to complete this assignment on your own.


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