Short answer: 2
(Sin(x) - Cos(x) )^2 = sin^2(x) - 2 sin(x)*cos(x) + cos^2(x)
(sin(x) + cos(x) )^2 = sin^2(x) + 2sin(x)*cos(x) + cos^2(x) Add these two
2sin^2(x) + 2cos^2(x) is all that is left. The two middle terms cancel out
Take out the common factor of 2
2(sin^2(x) + cos^2(x) )
but sin^2(x) + cos^2(x) = 1
2 * 1 = 2
2 <<<< answer
