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  2. Square pyramid - Wikipedia

    en.wikipedia.org/wiki/Square_pyramid

    A polyhedron's surface area is the sum of the areas of its faces. The surface area of a right square pyramid can be expressed as = +, where and are the areas of one of its triangles and its base, respectively. The area of a triangle is half of the product of its base and side, with the area of a square being the length of the side squared.

  3. Solid angle - Wikipedia

    en.wikipedia.org/wiki/Solid_angle

    The solid angle of an object that is very far away is roughly proportional to the ratio of area to squared distance. Here "area" means the area of the object when projected along the viewing direction. Any area on a sphere which is equal in area to the square of its radius, when observed from its center, subtends precisely one steradian.

  4. 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 ...

  5. 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 ...

  6. 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.

  7. Frustum - Wikipedia

    en.wikipedia.org/wiki/Frustum

    The Egyptians knew the correct formula for the volume of such a truncated square pyramid, but no proof of this equation is given in the Moscow papyrus. The volume of a conical or pyramidal frustum is the volume of the solid before slicing its "apex" off, minus the volume of this "apex":

  8. List of centroids - Wikipedia

    en.wikipedia.org/wiki/List_of_centroids

    Quarter-circular area [2] ... Right-rectangular pyramid: a, b = the sides of the base h = the distance is from base to the apex General triangular prism: b = the base ...

  9. Area - Wikipedia

    en.wikipedia.org/wiki/Area

    The formula for the surface area of a sphere is more difficult to derive: because a sphere has nonzero Gaussian curvature, it cannot be flattened out. The formula for the surface area of a sphere was first obtained by Archimedes in his work On the Sphere and Cylinder. The formula is: [6] A = 4πr 2 (sphere), where r is the radius of the sphere.