I'm currently in calculus 2 and we are learning about u-substitution and I am having a little bit of difficulty seeing how to start problems that involve trig functions. I know sometimes I can rewrite them to help suit my needs but this isn't always evident. I have for example the indefinite integral of sec^3(X)tan(x) and am pretty lost where to start something like this. Would I need to rewrite these terms or I can I just use u=sec(x)? If anyone knows of a way to go about these problems in general I would be greatly appreciative. Thanks in advance!