SOLUTION: Rewrite with only sin x and cos x. cos 2x

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Question 1082958: Rewrite with only sin x and cos x.
cos 2x - sin x
Answer by Theo(13342) (Show Source):
You can put this solution on YOUR website!
cos(2x) cos^2(x) - sin^2(x)

therefore:

cos(2x) - sin(x) becomes cos^2(x) - sin^2(x) - sin(x)

cos^2(x) - sin^2(x) can be factored to to be equivalent to (cos(x) - sin(x)) * (cos(x) + sin(x))

the expression becomes:

(cos(x) - sin(x)) * (cos(x) + sin(x)) - sin(x)

i believe that satisfies the requirement since the expression only contains cos(x) and sin(x).

cos(2x) = cos^2(x) - sin^2(x) is one of your trig identities.

cos^21(x) - sin^2(x) = (cos(x) - sin(x)) * (cos(x) + sin(x)) is derived from the basic algebraic identity that (a^2 - b^2) = (a-b) * (a+b).

SOLUTION: Rewrite with only sin x and cos x. cos 2x - sin x