Question

what is equivalent to (sin x + 1)(sin x − 1)?

Answer 1

(sin(x) + 1)(sin(x) - 1) = sin^2(x) - 1

sin^2(x) + cos^2(x) = 1
sin^2(x) - 1 + cos^2(x) = 0

Therefore:
sin^2(x) - 1 = -cos^2(x)

Answer 2

-cos2x?

Answer 3

THANK YOU!!!