Check the picture below
use the far-arc near-arc equation
bear in mind, your far-arc and near-arc are both in y-terms, so, the angle will be in y-terms as well
Step-by-step explanation:

Since they are multiples if 12
The possibilities are
12, 12, 156
12,24,144
12,36,132
12,48,120
12,60,108
12,72,96
12,84,84
24,24,132
24,36,120
24,48,108
24,60,96
24,72,84
36,36,108
36,48,96
36,60,84
36,72,72
48,48,84
48,60,72
60,60,60
Hence the probability is 1/19 or 0.0526
2 and 37/100 so I'm pretty sure yes it can be simplified