Template:Great circle distance/er/doc

Usage

{{Great circle distance/er|latitude}}

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

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

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.