# Spherical Circle Circumference

• Oct 13th 2009, 09:34 PM
Janu42
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?
• Oct 13th 2009, 11:33 PM
CaptainBlack
Quote:

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:

Attachment 13345

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

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