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
The Doll that Came Straight from Fairyland The Doll that Came Straight from Fairyland "The Doll That Came Straight From Fairyland" is a short story for children published in 1898 by the suffragist and children's fairytale writer Evelyn Sharp. The first edition was published by John Lane in London, England, in "All The Way To Fairyland" with seven other short stories. Evelyn Sharp was born in 1869 and was the ninth of eleven children. She had three years of schooling in London where she made her living. Evelyn's first publication was an article about fairy tales which led to "Wymps and other Fairy Tales" (1896) and "All