In Fig. PQ is a tangent to the circle with centre O. If ∠OPQ = x, ∠POQ = y, then x + y is:

(2)
Since PQ is tangent at Q to the circle and OQ is radius,
∴ OQ ? PQ ⇒ ∠OQP = 90°
In ΔPOQ, we have
∠OQP + ∠OPQ + ∠POQ = 180° [Angle Sum Property of triangle]
⇒ 90° + x + y = 180°
⇒ x + y = 180° – 90° = 90°