The figure above shows part of a circle whose circumference is 45. If arcs of length 2 and length b continue to alternate around the entire circle so that there are 18 arcs of each length, what is the degree measure of each of the arcs of length b?

a) 4

b) 6

c) 10

d) 16

e) 20

You know that 18(2 + *b*) = 45, so you can calculate *b*:

18(2 + *b*) = 45

36 + 18*b* = 45

18*b* = 9

*b* = 0.5

Now all you need to do to find the degree measure of an arc of length *b* is set up a ratio, like you do for LOTS of circle problems.