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 straight on, and when he meets other people he must ask what they are thinking. In his quest, he travels across the sea, through a gorse bush and over an iceberg to a castle. Along the way he collects thoughts. These thoughts consist of the Prince's wishes for his gift: a steamboat, a cannon and a magical balloon. The gifts that the Prince had wished for earlier help him reach the castle where Lady Emmelina is waiting. Once he finds her, the Prince quickly returns home. When Princess Pansy sees her brother she hugs him while Lady Emmelina falls to