NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Spherical right triangles, napiers circle
From: Patrick Stanistreet
Date: 2004 Jan 28, 07:57 -0800
From: Patrick Stanistreet
Date: 2004 Jan 28, 07:57 -0800
I have been going through a book Navigational applications of plane and spherical trigonometry by Carol Congleton, just trying to learn the math background involved. On a chapter concerning spherical right triangles are two rules which I would like to find a source for their derivation or a proof. Rule 1: the sine of a part is equal to the product of the tangents of the adjacent parts. Rule 2: the sine of a part is equal to the product of the cosines of the opposite parts. Also if anyone knows how Napiers circle was derived I would like understand the process.