Question: in figure 2 pq is a chord of a circle?
Answer: PQ is the chord of the circle and PT is tangent. We know that the tangent to a circle is perpendicular to the radius through the point of contact. ∠ OQP = ∠ OPQ = 30o (in a triangle, equal sides have equal angles opposite to them.) ... Hence, the measure of angle PRQ is 120o.