Area of a circle Area of a circle In geometry, the area enclosed by a circle of radius is . Here the Greek letter represents a constant, approximately equal to 3.14159, which is equal to the ratio of the circumference of any circle to its diameter. One method of deriving this formula, which originated with Archimedes, involves viewing the circle as the limit of a sequence of regular polygons. The area of a regular polygon is half its perimeter multiplied by the distance from its center to its sides, and the corresponding formula (that the area is half the perimeter times the radius, i.e.
Outer Circle railway line Outer Circle railway line The Outer Circle was built in 1891 as a steam-era suburban railway line, in Melbourne, Australia. It covered much of the modern City of Boroondara, including the suburbs of (from north to south) Kew East, Camberwell, Burwood, Ashburton, and Malvern East. At its longest stage, it ran from Fairfield station, on what is today the Hurstbridge line, to Oakleigh station, on the current Pakenham and Cranbourne lines. The Outer Circle railway was first advocated by a group known as the Upper Yarra Railway League in 1867 who suggested that the Gippsland Railway could be brought into