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  2. Solid angle - Wikipedia

    en.wikipedia.org/wiki/Solid_angle

    The solid angle of a four-sided right rectangular pyramid with apex angles a and b (dihedral angles measured to the opposite side faces of the pyramid) is = ⁡ (⁡ ⁡ ()). If both the side lengths ( α and β ) of the base of the pyramid and the distance ( d ) from the center of the base rectangle to the apex of the pyramid (the center of ...

  3. Surface area - Wikipedia

    en.wikipedia.org/wiki/Surface_area

    A sphere of radius r has surface area 4πr 2.. The surface area (symbol A) of a solid object is a measure of the total area that the surface of the object occupies. [1] The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of arc length of one-dimensional curves, or of the surface area for polyhedra (i.e., objects with ...

  4. Frustum - Wikipedia

    en.wikipedia.org/wiki/Frustum

    In geometry, a frustum (Latin for 'morsel'); [a] (pl.: frusta or frustums) is the portion of a solid (normally a pyramid or a cone) that lies between two parallel planes cutting the solid. In the case of a pyramid, the base faces are polygonal and the side faces are trapezoidal.

  5. Pyramid (geometry) - Wikipedia

    en.wikipedia.org/wiki/Pyramid_(geometry)

    In the case of a pyramid, its surface area is the sum of the area of triangles and the area of the polygonal base. The volume of a pyramid is the one-third product of the base's area and the height. The pyramid height is defined as the length of the line segment between the apex and its orthogonal projection on the base.

  6. Tetrahedron - Wikipedia

    en.wikipedia.org/wiki/Tetrahedron

    The volume of a tetrahedron can be obtained in many ways. It can be given by using the formula of the pyramid's volume: =. where is the base' area and is the height from the base to the apex. This applies for each of the four choices of the base, so the distances from the apices to the opposite faces are inversely proportional to the areas of ...

  7. Elongated triangular pyramid - Wikipedia

    en.wikipedia.org/wiki/Elongated_triangular_pyramid

    An elongated triangular pyramid with edge length has a height, by adding the height of a regular tetrahedron and a triangular prism: [4] (+). Its surface area can be calculated by adding the area of all eight equilateral triangles and three squares: [2] (+), and its volume can be calculated by slicing it into a regular tetrahedron and a prism, adding their volume up: [2]: ((+)).

  8. Egyptian geometry - Wikipedia

    en.wikipedia.org/wiki/Egyptian_geometry

    If the area of the Square is 434 units. The area of the circle is 433.7. The ostracon depicting this diagram was found near the Step Pyramid of Saqqara. A curve is divided into five sections and the height of the curve is given in cubits, palms, and digits in each of the sections. [3] [4] At some point, lengths were standardized by cubit rods ...

  9. Surface-area-to-volume ratio - Wikipedia

    en.wikipedia.org/wiki/Surface-area-to-volume_ratio

    Graphs of surface area, A against volume, V of the Platonic solids and a sphere, showing that the surface area decreases for rounder shapes, and the surface-area-to-volume ratio decreases with increasing volume. Their intercepts with the dashed lines show that when the volume increases 8 (2³) times, the surface area increases 4 (2²) times.