Question

PLESE HELP!
I know the answers but i have no idea how to get them.

1) Express cos θ (sec θ - cos θ), in terms of sin θ.

2) Find all values of θ in the interval 0° ≤ θ < 360° that satisfy the equation sin 2θ = sin θ.

Answer 1

Well, then you don't know the answers.

sec(x) = 1/cos(x)

sin^2(x) + cos^2(x) = 1

That's what you need for the first one.

You should memorize these identities.