Solid angle orientation formula_9, and distance from the viewer as: where the surface area of a sphere is . The solid angle of a cone with its apex at the apex of the solid angle, and with apex angle 2, is the area of a spherical cap on a unit sphere For small such that , this reduces to the area of a circle . The above is found by computing the following double integral using the unit surface element in spherical coordinates: This formula can also be derived without the use of calculus. Over 2200 years ago Archimedes proved that the
Solid surface then injected into the cavity of the mould. Many finishes are available including, gel coated, matte, gloss, metallic and textured. A "surface fabricator" shapes and installs functional and decorative surfaces, usually in buildings. Surface fabrication, as a distinct professional enterprise, usually involves complex tasks of surface shaping. A leading case is countertop fabrication. For interior spaces, surfaces include solid coverings or decking for floors or walls, and countertops for kitchens, bathrooms, and workspaces. Natural surfaces are composed of naturally occurring materials like wood, stone, mineral, clay, gum and resin. Synthetic surfaces contain, in addition to any natural materials, man-made substances