July 2nd, 2017, 01:13 PM  #1 
Newbie Joined: Jul 2017 From: moscow Posts: 2 Thanks: 0  Spherical triangle
I want to find angles of spherical traingle. The geographical coordinated of the points are 0, 0 0.000001, 0 0, 0.000001 I expect that agnles will be 90, a bit more than 45 and a bit more than 45 degrees. I use great circule distance formula and spherical cosine formula https://en.wikipedia.org/wiki/Greatcircle_distance https://en.wikipedia.org/wiki/Spherical_law_of_cosines The central angles are pretty small and they seems correct. They are 2,46827E8 1,74533E8 1,74533E8 But spherical law of cosines give strange results. I got the following angles in radians 0,687 0,687 1,9438 or in degrees 39,3627 39,3627 111,3746 It seems there is a mistake. Could you please help me. 
July 2nd, 2017, 03:02 PM  #2 
Global Moderator Joined: May 2007 Posts: 6,436 Thanks: 562 
It would be helpful if you showed intermediate results.

July 3rd, 2017, 06:03 PM  #3  
Global Moderator Joined: May 2007 Posts: 6,436 Thanks: 562 
You need to specify the radius of the sphere. Quote:
 
July 4th, 2017, 01:06 PM  #4 
Newbie Joined: Jul 2017 From: moscow Posts: 2 Thanks: 0 
Yes. They are central agnles in radians

July 4th, 2017, 01:40 PM  #5 
Global Moderator Joined: May 2007 Posts: 6,436 Thanks: 562  Central angles of what? Try to be specific. Also you need a radius for the sphere (1?). Last edited by mathman; July 4th, 2017 at 01:49 PM. 
July 5th, 2017, 06:21 PM  #6 
Global Moderator Joined: May 2007 Posts: 6,436 Thanks: 562 
I will assume the central angle is with reference to center of the sphere with radius 1. In that case the two equal sides have angles exactly equal to the sides (0.000001). The third side is very slightly less than sqrt(2) times other side length.


Tags 
law of cosines, spherical, triangle 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
spherical coords  Kinroh  Calculus  3  March 29th, 2015 08:28 AM 
PDE with source in spherical  jhartc  Differential Equations  0  December 6th, 2014 03:37 PM 
Spherical raindrop?  Shamieh  Calculus  17  September 25th, 2013 06:39 PM 
Spherical mirrors, spherical?  proglote  Physics  7  August 18th, 2011 12:29 AM 
Spherical & Euclidean....  TTB3  Real Analysis  2  February 16th, 2009 10:42 PM 