Answer:
Area of the border is 142.80 ft²
Step-by-step explanation:
The given figure consist of three figures = 2× semicircles + 1 square.
We will calculate area of the figure including border
Area of one semicircle = (1/2)π×r²= (1/2)×π×(12/2)² = (1/2)π×(6)² = 18π ft²
Area of square = side² = 12² = 144 ft²
Total area = 144 + 18π + 18π = (144 + 36π) ft²
Now we will calculate area without border.
Area of the semicircle = (1/2)π×r² =(1/2)π×[(12-4)/2]²=(1/2)π×(4)² = 8π ft²
area of square = side²= (12-4)²= 8² = 64 ft²
Total area = 64 + 8π + 8π = (64 + 16π) ft²
Now the area of the border = Area with border - Area without border
= (144 + 36π) - (64 + 16π) = 20π + (144 - 64) = 20π + 80
= 20×3.14 + 80 = 142.80 ft²
Area of the border = 142.80 ft²