Answer:
B) 236.25
Explanation:
POQ is a diameter of circle with centre O having diameter 21 cm. Whereas radius is 21/2 cm (as radius is considered as half of the diameter).
Assume that the tip of the triangle that touches the circle is point 'N'. So,
NO = radius = 21/2 cm
At present time we have a triangle of radius or height 21/2 cm, base 21 cm is enclosed in circle of diameter 21 cm. And are asked to find the area of the remaining region or you can say asked to find area of the shaded region.
Shaded region = Area of Circle - Area of Triangle
= πr² - 1/2 × b × h
= 22/7 × 21/2 × 21/2 - 1/2 × 21 × 21/2
= 21/2 × 1/2 [ 22/7 × 21 - 21 ]
= 21/4 [ 22 × 3 - 21 ]
= 21/4 [ 66 - 21 ]
= 21/4 [ 45 ]
= 21 × 11.25
= 236.25
Hence, the area of the shaded region is 236.25 cm².