Calculate sin(318°) knowing cos(42°) = 0.74

Question

What would be the procedure to find a trigonometric function value in terms of the value of another trigonometric function (evaluated in some angle)?

Would appreciate any help

Answer 1

Hint: Note that $\sin 318^\circ = \sin(-42^\circ) = -\sin42^\circ$.

Use the identity $\sin^2 x + \cos^2 x=1$.