PLS HELP

[hollow flame]

this is confusing me

[cold dust]

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[near ermine]

They are saying that you can get a big shaded semicircle if you translate the semicircle at the bottom to the white space left of the big semicircle

Then they look at the problem

Since each small semi circle has radius 2

It's area is half a circle with radius 2

Or

(4π) / 2

Since we want to count the shaded area and the left side of the big semicircle isn't shaded

We subtract that

So - (4π) / 2

And the area of the big semicircle is (16π) / 2

So the area of the shaded area is 8π + 2π - 2π

So we can see that the last two terms cancel out and we are left with 8π

And that should give the same answer as the one they gave

As a decimal

[forest jasper]

they're just adding the area of the big shaded semicircle disregarding the small white semi circled shape to the small shaded semicircle shape then deducting the white space from the big semircle