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 Road to Little Dribbling: More Notes from a Small Island The Road to Little Dribbling: More Notes from a Small Island The Road to Little Dribbling: More Notes From a Small Island is a humorous travel book by American author Bill Bryson, first published in 2015. Twenty years after the publication of "Notes From a Small Island", Bryson makes another journey around Great Britain to see what has changed. In the opening chapters he notes that the straight line distance from Bognor Regis on the south coast to Cape Wrath in Scotland is the longest straight line one can travel in the UK without crossing any part of the sea.