find area of circle
a=pir^2
d/2=r
20=d
20/2=r=10
a=pi10^2
a=pi100
a=100pi
so 15 squar miles
that is how much of the whole circle
15/100pi
ok, so the angle
360 is full circle
15/100pi=x/360
x is the angle
so usingn math
times both sides by 360
5400/100pi=x
54/pi=x
using calculator
17.1887≈x
about 17 degrees