How to This Eqa

Question

Cos² (2x) - cos² (6x) = Sin(4x)sin(8x)

Answer 1

You can write this as: (cos2x+cos6x)(cos2x-cos6x) Now,use cosA+cosB and cosA-cosB You can solve now?
 
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cos2(2x)−cos2(6x)?(cos(2x)−cos(6x))(cos(2x)+cos(6x))
So: Using: cos(C)+cos(D)=2cos(C+D/2)cos(C−D)/2)
                cos(C)−cos(D)=2sin(C+D/2)sin(D−C/2)
                (2sin(4x)sin(2x))(2cos(4x)cos(2x))
                ?(2sin(2x)cos(2x))⋅(2sin(4x)cos(4x))
                ?sin(4x)⋅sin(8x)