trig
posted by Sachiyo .
city A is 300 miles directly north of city B assuming the earth to be sphere of radius 4000 miles determine the difference in latitude in degrees of the two cities

arc length s = rθ
300 = 4000θ
3/40 = θ
that is in radians
In degrees, that's 180/pi * 3/40 = 4.3°
Check: a nautical mile is 1' of latitude, = 1.15 miles.
4.3° * 60'/° * 1.15mi/' =~ 300 mi