sin^2(pi-x) + cos(pi/2+x)

First, let's simplify the trigonometric functions.

sin(pi-x) = sin(pi)cos(x) - cos(pi)sin(x) = 0cos(x) - (-1)sin(x) = sin(x)

cos(pi/2+x) = cos(pi/2)cos(x) - sin(pi/2)sin(x) = 0cos(x) - 1sin(x) = -sin(x)

Now, substituting back into the original expression:

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

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

This expression cannot be further simplified without additional information on the values of x.