4MA0 Higher June 2013 Paper 3R Q20

20 \(PTR\) and \(QTS\) are chords of a circle.

\(PT = 3\) cm.
\(ST = 10\) cm.
\(RT = 15\) cm.
\(QT = x\) cm.

Diagram NOT accurately drawn

Calculate the value of \(x\).

(2)