SOLUTION: solve for x sinx*sin7x=sin3x*sin5x

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Question 1133852: solve for x
sinx*sin7x=sin3x*sin5x
Answer by t0hierry(194) About Me  (Show Source):
You can put this solution on YOUR website!

cos(x + 7x) - cos (7x -x ) =-2 sinx sin 7x
cos(5x + 3x) - cos(5x - 3x) =-2 sin5x sin 3x
cos(8x) - cos (6x) = cos(8x)- cos 2x
cos(6x) = cos(2x)
6x =2x + n pi
x = n pi/4