This could be any crazy number. But the derivative of this is still going to be cosine x. So when I say that we have to find an antiderivative, I'm just saying, look, we just have to find one of the derivatives. Sine of x is probably the simplest, because in this case, the constant is 0. So let's evaluate. So one way that we can denote this, the antiderivative of cosine of x, or an antiderivative of cosine of x, is sine of x. And we're going to evaluate it at pi over 2.