1.

Prove that:`cos^2 2x-cos^2 6x=sin4xsin8x`

Answer» LHS `=cos^(2)2x-cos^(2)6x`
`=1/2[2cos^(2)2x-2cos^(2)6x]`
`=1/2[cos4x-cos12x]`
`=1/2[2sin(4x+12x)/(2)sin(12x-4x)/(2)]`
`=sin8xsin4x=sin4xsin8x` = R.H.S. Hence Proved.


Discussion

No Comment Found

Related InterviewSolutions