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Please help with explanation

Please help with explanation-example-1

1 Answer

8 votes

Answer:

B

Explanation:

The formula for a area of the first semi circle is


(1)/(2) * \pi {r}^(2)

where r is the radius

Since 4 is the diameter, 2 is the radius

plug it in


(1)/(2) * \pi {2}^(2)


(1)/(2) * 4\pi


2\pi

so the area of the first circle is 2


2\pi

now let find the second circle

Since the semi circle is twice the area of AB the diameter is 8 so the radius is 4.

Put it in the equation.


(1)/(2) * \pi {4}^(2)


(1)/(2) * \pi * 16


8\pi

Now let find the third circle

Since it is twice the size of the second circle, the diameter is 16 and the radius is 8.


(1)/(2) * \pi {8}^(2)


(1)/(2) * 64\pi


32\pi

Now let add the area of the semi circle


32\pi + 2\pi + 8\pi = 42\pi

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