It is easy to prove RSQP is cyclic; so that this can be easily shown in many ways.

e.g.

Let angle AQS = @; .: angle QBS = @; .: angle PRS = @ (PR // QB)

.: angle AQS = angle PRS

.: external angle AQS of quadrilateral RSQP = int opp angle PRS

.: RSQP must be cyclic

QED

## Bookmarks