A circle is 360 all the way around. Make sure you dont mix up arc length with the measure of an arc which is the degree size of its central angle. An arc is a part of the circumference of a circle.
We know that for the angle equal to 360 degrees 2p the arc length is equal to circumference.
Plugging our radius of 3 into the formula we get C 6p meters or approximately 188495559 m. The arc length is frac 1 4 times pi times 8 2 pi. Rounded to 3 significant figures the arc length is 628cm. From this point on we are going to use the following formula for the length of the curve.