I know how to integrate sec^3x using integration by parts. I struggled heavily trying to figure it out on my own so I looked up the solution for it. However, I came across the Weierstrass substitution method or the "nuclear option". I wanted to practice the Weierstrass method but even then, I'm struggling with this method as well. So how to I proceed with this integral? (Sorry if some of my "t"s look like plus signs.)