When you see a sin^2 , a plus sign, and a cos^2 , a little bell should ring in your
head. Remember this key trigonometric identity:
sin^2 x + cos^2 x =1For any angle x, take the sine and cosine, square them both, and the squares
will add up to 1. (This relationship is really just a variation of the Pythagorean
theorem.) The test makers love this identity—it turns up a lot. So keep your
eye out for it.
Here in Example 2, when you spot “6 sin^2 x + 6 cos^2 x,” you should think
immediately about how to extract “sin^2 x + cos^2 x” from it. You do that by
factoring out a 6.
The answer is (B).