I have thirteen obnoxious super large bumper stickers, but only a small amount of room on my tailgate. How many ways can I choose a set of three of them (the order doesn't matter)

arc length = 6.63311 ft.

step-by-step explanation:

the formula the arc measure is:

arc length s=2πr(c)/360

where:

c   is the central angle of the arc in degrees

r   is the radius of the arc

π   is pi, approximately 3.142

using the above formula we get

s =

thus we find that arc length of an arc for a circle of radius 20 feet and central angle 19 degrees is

6.63311 feet

any of them that add up to 180 degrees.