Points A and B are on a circle with centre O. PA and PB are tangents to the circle from an external point P. If PA and PB are inclined to each other at $$42^{\circ}$$, then find the measure of $$\angle$$ OAB.

A

$$21^{\circ}$$

B

$$69^{\circ}$$

C

$$42^{\circ}$$

D

$$25^{\circ}$$