Exact answer = 6pi
Approximate answer = 18.84 (when you use pi = 3.14)
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Step-by-step explanation:
The diameter is 12, so the circumference of the full circle would be
C = pi*d
C = pi*12
C = 12pi
But we don't want the full distance around the circle. Instead we want half the distance to get the arc length of the semicircle. So we just take half of 12pi to get 6pi.
The exact arc length is 6pi, which is approximately 18.84 when you use pi = 3.14