Rewrite

so that it involves only the first power of cosine

All you need is the double angle identity:

So we have

Apply the identity again to the squared term:

step-by-step explanation:

subtract 7, so the answer is x < = 3, or c.

-7

step-by-step explanation:

x^2 + 18x + 74 = (x + 9)^2 - 81 + 74

= (x + 9)^2 - 7.

so q = -7.