A secant PAB is drawn from an external point P to the circle with the centre at O, intersecting it at A and B. If OP = 17 cm, PA = 12 cm and PB = 22.5 cm, then the radius of the circle is:
1
\(\sqrt{23} \, \text{cm}\)
2
\(\sqrt{21} \, \text{cm}\)
3
\(\sqrt{17} \, \text{cm}\)
4
\(\sqrt{19} \, \text{cm}\)