Solid angle to the unit sphere with center P, which can be calculated as the surface integral: where formula_5 is the unit vector corresponding to formula_6, the position vector of an infinitesimal area of surface with respect to point P, and where formula_7 represents the unit normal vector to . Even if the projection on the unit sphere to the surface S is not isomorphic, the multiple folds are correctly considered according to the surface orientation described by the sign of the scalar product formula_8. Thus one can approximate the solid angle subtended by a small facet having flat surface area ,
Solid surface manufactured in sheet form for fabrication into finished countertops, solid surface can also be cast into a variety of shapes, including sinks, shower pans and bathtubs. Sheet goods can also be heated and bent into three-dimensional shapes using a process called thermoforming, which adds to the versatility of the product. Color and design flexibility are key factors when choosing engineered composites over natural stone. In a residential setting, solid surface can be used as kitchen countertops, bathroom vanity tops, and shower and tub surrounds. Countertop fabricators typically join solid surface sheets into desired shapes using a two-part adhesive, after which