(a)[2]
Calculate the value of $x$. State a geometrical reason for your answer.
(b)[3]
Calculate the value of $y$.
Mathematics 0580 · IGCSE · Circle theorems I
Circle theorems I — practice question
The diagram depicts a circle with centre $O$. $P$ and $S$ lie on the circle. $POR$ is a straight line. $QRST$ is tangent to the circle at $S$. The marked angles are $25^{\circ}$ at $P$, $x^{\circ}$ at $S$, and $y^{\circ}$ at $R$ on the tangent.