Answer:
Step-by-step explanation:
The formula to find arc length is
[tex]AL=\frac{\theta}{360}*\pi d[/tex] where theta is the measure of the central angle and d is the diameter. If we are dealing with a semicircle, the measure of the central angle is 180 degrees. Filling in:
[tex]AL=\frac{180}{360}*\pi (18)[/tex] which simplifies a bit to
[tex]AL=\frac{1}{2}*\pi (18)[/tex] and a bit more to
AL = 9π. That answer is obviously in terms of π; if you need it in terms of whatever your measurement is (feet, inches, cm, etc.) the answer would be, rounded to the nearest tenth, 28.3 units
