Solve the equation `sin^3x.cos3x+cos^3x.sin3x+3/8=0`

Explanation

`sin^3xcos3x+cos^3xsin3x +3/8 = 0`

`=>sin^3x(4cos^3x - 3cosx)+cos^3x(3sinx-4sin^3x)+3/8 = 0`

`=>4sin^3xcos^3x - 3cosxsin^3x+3sinxcos^3x - 4sin^3xcos^3x +3/8 = 0`

`=>3sinxcosx(cos^2x-sin^2x) = -3/8`

`=>8sinxcosx(cos2x) = -1`

`=>4sin2xcos2x = -1~

`=>2sin4x = -1`

=>sin4x = -1/2`

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