of a point P in a plane can be described by giving its distance
r from a fixed point O, called the pole, and the angle θ
of OP from
a fixed direction. The coordinates of P are given as (r,θ) and known
as polar coordinates.
When the position of a ship or an aircraft
is given relative to its base by using its distance from base and
its bearing from the base, then polar coordinates are being used.