Please solve question no.20.

Dear Student,
Solution) 
20(i) Area of the whole semicircle:
Area = 1/2 πr²
Area = 1/2 π(14)² = 308 cm²
Area of the unshaded semicircle:
Area = Area = 1/2 πr²
Area = 1/2 π(14 ÷ 2)² = 77 cm²
Now,
Area of the shaded semicircle:
Area = 308 - 77 = 231 cm²

(ii) L​​​​ength of the base of the triangle:
Area of triangle = 1/2 x base x height
35 = 1/2 x base x 5
35  5/2 x base
base = 35 ÷ 5/2
base = 14 cm
Area of the semicircle:
Area of the circle =1/2 πr²
Area of the circle =1/2 π(14 ÷ 2)² = 77 cm²
Area of the shaded region:
Area of the shaded region = 77 - 35 = 42 cm²


Regards!