Question

The radius of a circle is 3 feet. What is the length of a 180° arc?

Answer 1

s = r*theta
s = arc length
r = radius
theta = angle measure in radians. If given in degrees you must change to radians.

s = 3 * 180 * (pi/180)
s = 3 pi ft.
This is the exact value.
s = 9.42 ft. Is the decimal approximation.