Drumlin Drumlin A drumlin, from the Irish word "droimnín" ("littlest ridge"), first recorded in 1833, and in the classical sense is an elongated hill in the shape of an inverted spoon or half-buried egg formed by glacial ice acting on underlying unconsolidated till or ground moraine. Drumlins occur in various shapes and sizes, including symmetrical (about the long axis), spindle, parabolic forms, together with transverse asymmetrical forms; their long axis is parallel to the direction of movement of the formative flow at the time of formation. Drumlins are typically long, less than high and between wide. Drumlins generally have a length:width
Elongated triangular orthobicupola = 4 tetrahedra, so total we have 20 tetrahedra. What is the volume of a tetrahedron? Construct a tetrahedron having vertices in common with alternate vertices of a cube (of side formula_1, if tetrahedron has unit edges). The 4 triangular pyramids left if the tetrahedron is removed from the cube form half an octahedron = 2 tetrahedra. So formula_2 The hexagonal prism is more straightforward. The hexagon has area formula_3, so formula_4 Finally formula_5 numerical value: formula_6 The elongated triangular orthobicupola forms space-filling honeycombs with tetrahedra and square pyramids.<br> Elongated triangular orthobicupola In geometry, the elongated triangular orthobicupola is one