Answer:
2pi or approximately 6.28
Explanation:
The perimeter of a circle is called the circumference
A semicircle is 1/2 of the circle so we want 1/2 of the circumference
1/2 C = 1/2 pi*d where d is the diameter
= 1/2 pi *4
=2pi
We can approximate pi by 3.14
= 2(3.14) = 6.28