I believe the question is simply asking you to re-arrange that equation to get 2 different ones.
Basically solve for sin(θ) and cos(θ).
What is sin(θ) equal to in terms of cos(θ) & tan(θ)?
What is cos(θ) equal to in terms of sin(θ) & tan(θ)?
Hint: One of those two is a fraction, while the other is a product.