Question 107764
There are 22 teeth and 22 spaces between them.
The Circumference - the amount of space taken by the teeth (22s where s is the amount of space taken by one tooth) is equal to the total amount of space occupied by nothing ... Divide that by the 22 spaces between the teeth and you get the individual space between two teeth.
(C - 22s)/22
(18(pi) - 22s)/22
9(pi)/11 - s    ... where s is in cm