8 research outputs found
Volume formula for a -symmetric spherical tetrahedron through its edge lengths
The present paper considers volume formulae, as well as trigonometric
identities, that hold for a tetrahedron in 3-dimensional spherical space of
constant sectional curvature +1. The tetrahedron possesses a certain symmetry:
namely rotation through angle in the middle points of a certain pair of
its skew edges.Comment: 27 pages, 2 figures; enhanced and improved exposition, typos
corrected; Arkiv foer Matematik, 201
Volumes of polytopes in spaces of constant curvature
We overview the volume calculations for polyhedra in Euclidean, spherical and
hyperbolic spaces. We prove the Sforza formula for the volume of an arbitrary
tetrahedron in and . We also present some results, which provide a
solution for Seidel problem on the volume of non-Euclidean tetrahedron.
Finally, we consider a convex hyperbolic quadrilateral inscribed in a circle,
horocycle or one branch of equidistant curve. This is a natural hyperbolic
analog of the cyclic quadrilateral in the Euclidean plane. We find a few
versions of the Brahmagupta formula for the area of such quadrilateral. We also
present a formula for the area of a hyperbolic trapezoid.Comment: 22 pages, 9 figures, 58 reference
GEOMETRY OF TREFOIL CONE \u2013 MANIFOLD
In this paper we prove that Trefoil knot cone manifold T (\u3b1) with cone
angle \u3b1 is spherical for \u3c0/3 < \u3b1 < 5\u3c0/3. We show also that its spherical volume is
given by the formula Vol(T (\u3b1)) = (3\u3b1 12 \u3c0)2 /12