Answer : (c) 60 sq. units
∠PQS = ∠PRS = 90º (Angle in a semicircle)
∵ QS || PR, ∴ ∠QPR = ∠QSR = 90º
∴ PQSR is a rectangle as a pair of opposite sides is parallel and all angles are 90º.
⇒ PR = QS and PQ = RS
⇒ PQ = QS = RS = PR = 10√2 cm. Hence PQSR is a square.
∴ Diagonal PS of the square = Diameter of the circle
= 10 √2 × √2 = 20 cm.
∴ The radius of the circle = 10 cm.
Hence, Area of shaded portion = Area of semi-circle – Area of △PQS
= (157 - 100) cm2 = 57 cm2
≈ 60 cm2