Primitive of Arcsine of x over a over x

Also see

 * Primitive of $\dfrac {\arccos \frac x a} x$
 * Primitive of $\dfrac {\arctan \frac x a} x$
 * Primitive of $\dfrac {\operatorname{arccot} \frac x a} x$
 * Primitive of $\dfrac {\operatorname{arcsec} \frac x a} x$
 * Primitive of $\dfrac {\operatorname{arccsc} \frac x a} x$