Answer:
(a) 12.96 ft²
(b) 21.5 in²
Explanation:
(a) For the first diagram
Area of the shaded region (A) = Area of Tripezium- area of circle
A = [1/2(a+b)h]-[πr²]............... Equation 1
Where a and b are the parallel side of the tripezium respectively, h = height of the tripezium, r = radius of the circle.
From the diagram,
Given: a = 15 ft, b = 6 ft, h = 12 ft, r = h/2 = 12/2 = 6 ft.
Constant: π = 3.14
Substitute these values into equation 1
A = [12(15+6)/2]-(3.14×6²)
A = 126-113.04
A = 12.96 ft²
(b) For the second diagram,
Area of the shaded region (A') = Area of square- area of circle
A' = (L²)-(πr²)............. Equation 2
Where L = lenght of one side of the square, r = radius of the circle
From the diagram,
Given: L = 2r = (2×5) = 10 in, r = 5 in
Substitute these values into equation 2
A' = (10²)-(3.14×5²)
A' = 100-78.5
A = 21.5 in²