Similar triangles from the alternate segment theorem

In the diagram, \(A\), \(B\) and \(T\) lie on a circle. \(PT\) is the tangent to the circle at \(T\), and the line from \(P\) cuts the circle at \(A\) and \(B\).

(i) Prove that \(\triangle PTA\) is similar to \(\triangle PBT\).
(ii) Hence show that \(PT^2=PA\times PB\).