



 
We have two responses for you Hi Lenny, The length a of an arc is given by
if r is the radius of the arc, θ is the angle measured in radians and the units are the same as the units used to measure the radius. There are π radians in 180^{o} so if you measure the angle in degrees the length of the arc is given by
Thus if the angle is 50^{o } then the length of the arc is
Penny
Hi Lenny. The easiest way is this:
For example, if I have a 45 degree sector of a circle whose radius is 5, then I know the whole circumference is 10pi. The ratio of the degrees of the sector to the whole circle is 45/360, which is just 1/8. So the arc length is 1/8 of 10pi. Hope this helps,  


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