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
Distance from a point to a line to the point P. Hence: We can solve this equation for "x", The y coordinate of the point of intersection can be found by substituting this value of "x" into the equation of the original line, Using the equation for finding the distance between 2 points, formula_35, we can deduce that the formula to find the shortest distance between a line and a point is the following: Recalling that "m" = -"a"/"b" and "k" = - "c"/"b" for the line with equation "ax" + "by" + c = 0, a little algebraic simplification reduces this to the standard expression. The