1) sin6x ( sinx ) = cos3x ( cos4x )………ans.: (2npi )/3 +/- pi/6, npi +/- 0.284, npi +/- 1.103 2) cos3x = cos2x ( cosx )……..ans.: npi / 2 3) tanx = cotx…………ans.: npi/2 + pi/4 Here are the steps of 3, but why this method is wrong? tanx = cotx tan^2 x= 1 sin^2 x / cos ^ 2 x = 1 sin^2 x = cos^2 x cos^2 x – sin^2 x = 0 cos2x = 0 2x = 2npi +/- pi/ 2 x = npi +/- pi / 4