14 Jul
2007
14 Jul
'07
4:23 p.m.
On 7/14/07, Fred lunnon <fred.lunnon@gmail.com> wrote:
... This looks suspiciously like the area formula for the dual spherical polygon: this has angles and sides corresponding to the sides and angles of the of the original polygon (whose angles corrspond to dihedral angles, and sides to apical angles). See Todhunter. WFL
I ought to have mentioned that if a spherical triangle has sides a,b,c and angles A,B,C, then its dual is the triangle with sides \pi - A, \pi - B, \pi - C, and angles \pi - a, \pi - b, \pi - c. There is a neat construction relating the two, which I can never remember how to do ... WFL