Simplify the expression by using a double-angle formula or a half-angle formula. (a) cos2 θ 2 − sin2 θ 2

If this is supposed to be

Then this can simply be reduced to

by the double angle formula for cosine

32

step-by-step explanation:

these are your clues: 1. kim ran 18 races2. this was four fewer races than twice thenumber, notice it says twice the number, so you would do the equation 18x2-4; which equals the number 32.thus, 32 is your answer.