Evaluate the indefinite integrals using Substitution. (use $C$ for the constant of integration.)

a) $\displaystyle \int \tan(5 x) \, dx =$
Hint: First rewrite $\tan(5 x)$ in terms of sine and cosine.

b) $\displaystyle \int \sec(5 x) \, dx =$
Hint: First multiply and divide by $\sec(5 x) + \tan(5 x)$.