the shortest distance between two points P, Q on the surface of the sphere of radius R
if we know longitude (east-west position), latitude (north-south position) of P and Q
If you have to put a coefficient using some other function symbol (for example √2; π/2), put it in a numerical form
(1.414213562373095, 1.5707963267949), for example using this (or this).
[NaN = "not a number"]