PA and PB are tangents to a circle with centre O. if angle AOB = 120 degree then find angle OPA. Share with your friends Share 1 Anuradha Sharma answered this Since tangents and radius are perpendicular so∠OAP=∠OBP=90 degreeand by symmetry, ∠AOP=∠BOP=60 degreeSo in triangle OPA, ∠OAP+∠OPA+∠AOP=180∠OPA=180-90-60=30 degree -1 View Full Answer