Elements of Spherical Trigonometry

A+B+C Acos B₁ ccos centre CHAPTER chordal triangle circles cos.² cos.a cos cos.a cos.b cos.c cosines ctan deduce determine dihedral angles equation equiangular equiangular polygon geometrical given gives greater Hence hypothenuse less than 90 limit logarithms Lune to angle nearly number of edges number of faces number of sides O₁ oblique-angled triangles opposite angles pentagons perpendicular plane angles plane triangle PO.OQ positive preceding formulæ quadrilaterals R₁ radius rectilinear angles rectilinear triangle regular solids remaining angles right angles right-angled spherical triangle right-angled triangles side or angle sides and angles sin.² sin.c sin.º sine solid angle spherical excess spherical polygons SPHERICAL TRIGONOMETRY Substitute subtended supplemental triangle three angles three planes Treatise on Geometry triangle A B C vers whence whole number αβ