Definitions from Trigonometric integrals
All definitions from Trigonometric integrals.
[DEFINITION]The identities used to integrate ∫tanmxsecnxdx are
1+tan2x=sec2x,dxdtanx=sec2x,dxdsecx=tanxsecx.The two derivative identities are why u=tanx and u=secx match a leftover factor of sec2x or tanxsecx.