A semicircle is exactly half a circle, so take the formula for circumference (C = 2πr) and divide by 2. Since r = 2, you end up with (2π(2))/2 = 2π. That covers the curved part.
You know the straight part has a length of 4 because the radius of the semicircle is 2.
4 + 2π is your answer.
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