# Collinear Proof in Circle Geometry

(a) $\ \$ Show that $\angle DSR = \angle DAR$. The quadrilateral $DRAS$ is cyclic, since $\angle DRA + \angle DSA = \pi (180^{\circ})$. Therefore $\angle DSR = \angle DAR$ (angles in the same segment of circle $DRAS$, both standing on same chord […]