Template:Great circle distance/er/doc

Usage

Calculates the Earth's radius, in kilometers, at a given latitude. Uses the following formula:

$R = \sqrt{[(r_{1}^{2} * \cos B)^{2} + (r_{2}^{2} * \sin B)^{2}] / [(r_{1} * \cos B)^{2} + (r_{2} * s i n B)^{2}]}$

with latitude $B$ , radius $R$ , radius at equator $r_{1} = 6378.137$ , and radius at pole $r_{2} = 6356.752$

With no latitude input, it defaults to the mean Earth radius.