Question

Use basic identities to simplify the expression.

cos θ - cos θ sin^2θ

Answer 1

please help.

Answer 2

cos θ (1-sin^2θ) = cos θ(cos^2 θ) = cos^3 θ

Answer 3

Can you show me which rules you used?

Answer 4

I factored, first. cos θ(1-sin^2 θ) = cos θ - cos θ sin^2 θ.
Remember your pythagorean identities.
One of them being sin^2 θ +cos^2 θ = 1.
So, with this information, you can see cos^2 θ = 1 - sin^2 θ if you take away the sin^2 θ on the right side of the equation/identity.

Answer 5

Oh. okay, thank.