The complex numbers \(s,t\) are \(s=3(\cos2+\mathrm i\sin2)\) and \(t=2\mathrm e^{-\mathrm i}\).

(a) Express \(st\) in the form \(r\mathrm e^{\mathrm i\theta}\), where \(-\pi<\theta\le\pi\) and \(r>0\). [2]

On an Argand diagram with origin \(O\), points \(A,B\) represent \(s,st\), respectively.

(b) By considering \(OA\) and \(OB\), or otherwise, state the two geometric effects on \(OA\) of multiplying \(s\) by \(t\). [2]