Spherical geometry
Category. The right-angled spherical triangle
NAKED RULE
If the cathetus a is replaced (90° — ∝), the cathetus b through
(90° — b) and doesn't count the right angle, so applies:
The cosine of any piece is equal to the product of the cotangents of the adjacent pieces and equal to the product of the sines of the non-adjacent pieces.
B. The general spherical triangle