I need help on a) & b) thank you!

25. The circumference of a circle of radius r is Oh") = Eat". a) If r is measured in meters, what are the units of C and (3\"? Are the units of C\" the same as the units of C divided by the units of r? 1)} Compute the derivative {3'11\"} Does it have the right units according to part (a)? c) Hoer much does the circumference of a circle change if we increase its radius from 100 meters to 101 meters? d) Imagine that the Earth is a perfect sphere, and that a giant belt, about 24,000 miles long is placed along the equator. How much fabric would have to he added to the belt to raise it one inch (everywhere) above the ground? _.. -:____._;-_.. .-_ |'-_'_'.'_'_'._n' " _'___