Primitive of Arctangent of x over a over x

Also see

 * Primitive of $\dfrac {\arcsin \dfrac x a} x$


 * Primitive of $\dfrac {\arccos \dfrac x a} x$


 * Primitive of $\dfrac {\arccot \dfrac x a} x$


 * Primitive of $\dfrac {\arcsec \dfrac x a} x$


 * Primitive of $\dfrac {\arccsc \dfrac x a} x$