If PA and PB are tangents to a circle with centre O and angle APB = 90°, then AOBP is a _____.
parallelogram
rectangle
square
rhombus
If PA and PB are two tangents to a circle with centre O such that ∠ AOB = 110o then ∠ APB is equal to
(a) 55o (b) 60o (c) 70o (d) 90o