Solve `sin 2x - sin 4x + sin 6x = 0`.

Explanation

`sin2x- sin4x+ sin6x = 0`

as we know that, `(sina + sinb = 2sin((a+b)/2)cos((a-b)/2))`

so, `2sin4x.cos(-2x) - sin4x = 0`

`= Sin4x(2cos2x-1) = 0`

now it can possible that whether `sin4x = 0 or 2cos2x-1=0`

when `sin 4x=0`

`4x = n pi & n in z`

`x= npi/4`

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