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

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.