An equestrian club orders magazine subscriptions for new members.
2 answers:
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Arc length has a formula that is similar to arc measure, but arc length is expressed in inches or meters or miles, etc., whereas measure is expressed in degrees, like an angle. The formula for each take this into account. Since the arc length is part of the length of the outside of the circle, the formula includes the circumference for a circle. 
, where theta is the degree measure of the central angle intersecting the arc you're looking for, and d is the diameter of the circle. Our formula would look like this with the info we have: 
which can be simplified to 
which can be simplified even further to 
. And that's your answer!