If sin x+sin2x=1, then the value of cos12x+3 cos10x+3 cos8x+cos6x−1 is equal to
0
From sin x+sin2x=1, we get sin x=cos2x, Now, the given expression is equal to cos6x(cos6x+3cos4x+3 cos2x+1)−1=cos6 x(cos2 x+1)3−1=sin3x(sin x+1)3−1=(sin2x+sinx)3−1=1−1=0