(3) Let PQ be the chord, KP and KQbe the radii with K as centre.
SinceKP PQ =PQ=KQ , triangle KPQ is an equilateral. So, ∠ PKQ 60° As angle made by an arc at centreis half of the angle made by it at circumference, therefore, ∠PSQ=30° since, PSOR is a cyclic quadrilateral, ∠PSQ+anglemathrmPRQ=180° 30°+∠PRQ=180°⇒∠PRQ=150°