1. ## Spherical Circle Circumference

Suppose I travel r distance away from the north pole and then made a spherical circle at this distance (essentially a line of latitude). How do I figure out the circumference of this spherical circle?

2. Originally Posted by Janu42
Suppose I travel r distance away from the north pole and then made a spherical circle at this distance (essentially a line of latitude). How do I figure out the circumference of this spherical circle?
Draw a diagram:

$\rho$ is the radius to be used in calculation of the circumference, and:

$\sin(r/R)=\rho/R$
CB