So we need to take the antiderivative of sine of pi x. The derivative of cosine of x is negative sine x. The derivative of cosine of pi x is negative pi cosine of pi x. So the antiderivative of sine of pi x is going to be negative 1 over pi cosine of pi x. And you can verify it for yourself. And you might say, wait, how did you know it was a negative? Well, I put the negative there so that when I take the derivative of the cosine of pi x, I would get a negative sign.