Problem: Assume that the earth is a sphere of radius 5280 miles, find the length of the sides, the measure of the angles and the area of the spherical triangle with vertices A(70°N,10°E),B(10°S,100°E) and C(50°S,80°W). The earth's radius will be used as the unit of length. The spherical coordinates (r,v,u) of the three vertices are (1,10,20),(1,100,100) and (1,−80,140)
How did they obtain the spherical coordinates? meaning (r,v,u). So for example how did they get (1,10,20). I'm assuming the radius is 1 which is r, v=angle but i'm not sure why it is -80 and i have no idea what u could be.