So cosine squared of u of x, u of x. So that's the derivative of secant with respect to u of x, and then the chain rule tells us it's gonna be that times u prime, u prime of x. So what is this going to be equal to? Well, I could just substitute back. This is going to be equal to, I will write it like this, sine of u of x, which is three pi over two minus x, and I'll fill that in in a second, over cosine of u of x squared times u prime of x. U of x is three pi over two minus x. Three pi over two minus x. And then u prime of x, we already figured out is negative one, so I could write times negative one.