How would I find the antiderivative of this equation?

S 0 to pi/3 (1-secxtans)dx

This should be one that you should just recognize from your study of trig derivatives.

Isn't the derivative of sec x, or (cos x)^-1
-(cos x)^-2(-sin x) ??
and isn't that sinx/cosx (1/cosx) ?
and isn't that tanxsecx ??

Can you take it from there?