I hope this won't win the record for being the easiest question on this site, but I'm having trouble finding the area of this figure.
I can use the circle formula to find the area of the circle with radius 3.5m, then I can subtract that from the overall shape. However, I can't see all measurements present.
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$\begingroup$After combining the two half circles, we get a circle with a diameter of 7.8 m. By dividing the diameter by two, we get the radius, 3.9 m. We can find the area of this circle and divide by two to get the area of the half circles. π*3.9^2 ≈ 47.78. 47.78/2 = 23.89. So each half circle ≈ 23.89 m². To get the area of the inner rectangle, we need to find the length, which we can do by subtracting 2*the radius of the combined half circles from 18. 18-7.8 = 10.2. We can now find the area of the inner rectangle: 7.8*10.2 = 79.56 m². To find the area of only the shaded part of the inner rectangle, we subtract the area of the circle (π*3.9^2 = 38.48 m²) from 79.56 m². 79.56 m² - 38.48 m² = 41.08 m². To find the area of the entire shaded portion, we can just add the area of the half circles and the area of the inner circle: 23.89 m² + 23.89 m² + 41.08 m² = 88.86 m².
The shaded portion has an area of 88.86 m².
$\endgroup$ $\begingroup$If you fill in the inner circle, then I see a circle of diameter 7.8 and a 7.8 by 10.2 rectangle. Find that area, then remove the circle of radius 3.5 to get the actual shaded area.
$\endgroup$ $\begingroup$Alright.
So first find the area of the whole figure, which is essentially the sum of two semicircles of radii 3.9 cm and the rectangle in the middle which is: $7.8 * 10.2 + \pi*(3.9)^2 $. You can then subtract the white circle's area to give you the required answer.
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