Rewrite with only sin x and cos x.

cos 2x - sin x

Select one:

a. cos2x - sin2x - sin x

b. cos2x - sin3x

c. cos2x + sin2x + sin x

d. cos2x - 3 sin x

The answer is a. cos2x - sin2x - sin x. Use the rule: cos2x = (cos^2) x - (sin^2) x. So, substitute cos2x in the expression: cos2x - sinx = ((cos^2) x - (sin^2) x) - sinx = (cos^2) x - (sin^2) x - sinx. Therefore, choice a. is correct choice.