Show that, for any values of $x$ and $y$ where $x> y$,

- the angle $SPQ$ is always the same and find this angle
- the angle $SRQ$ is always the same and find this angle
- the quadrilateral $SPQR$ is cyclic
- the angle $PQR$ is always the same and find this angle
- the angle $PSR$ is always the same and find this angle.