I used a set of compasses and drew out the first few cases
N Subtending Angle Fraction Of Circumference = arc length = angle* (R = 1/2pi)
2 2pi 1 = 4/2N
3 5pi/3 5/6 = 5/2N
4 3pi/2 3/4 = 6/2N
5 did not draw because the 5 was too much of a bother
6 4pi/3 2/3 = 8/2N
.
N (N+2)/2N
Total arc = (N+2)/2N * 1 *N = (N+2)/2
(N+2)/2 = 60
N = 118
I used a set of compasses and drew out the first few cases
N Subtending Angle Fraction Of Circumference = arc length = angle* (R = 1/2pi)
2 2pi 1 = 4/2N
3 5pi/3 5/6 = 5/2N
4 3pi/2 3/4 = 6/2N
5 did not draw because the 5 was too much of a bother
6 4pi/3 2/3 = 8/2N
.
.
N (N+2)/2N
Total arc = (N+2)/2N * 1 *N = (N+2)/2
(N+2)/2 = 60
N = 118