Circle a triangle whose base has the length of the circle's circumference and whose height equals the circle's radius, which comes to multiplied by the radius squared: Equivalently, denoting diameter by "d", that is, approximately 79% of the circumscribing square (whose side is of length "d"). The circle is the plane curve enclosing the maximum area for a given arc length. This relates the circle to a problem in the calculus of variations, namely the isoperimetric inequality. Equation of a circle<br> In an "x"–"y" Cartesian coordinate system, the circle with centre coordinates ("a", "b") and radius "r" is the set of
There Is a Light That Never Goes Out There Is a Light That Never Goes Out "There Is a Light That Never Goes Out" is a song by the English rock band the Smiths, written by guitarist Johnny Marr and singer Morrissey. Featured on the band's third studio album "The Queen Is Dead", it was not released as a single in the United Kingdom until 1992, five years after their split. It peaked at No. 25 on the UK Singles Chart. The song has received considerable critical acclaim; in 2014, "NME" listed "There Is a Light That Never Goes Out" as the 12th greatest song of all time.