\begin{ccRefFunction}{coplanar}
\ccFunction{bool coplanar(const Point_3<R> &p,
const Point_3<R>&q,
const Point_3<R>&r,
const Point_3<R>&s);}
{returns \ccStyle{true}, if $p$, $q$, $r$, and $s$ are coplanar.}
\end{ccRefFunction}