To describe the position of a table lamp placed on the table, let us consider the table lamp as P and the table as a plane.Now choose two perpendicular edges of the table as the axes OX and OY.Measure the perpendicular distance ‘a’cm of P (lamp) from OY. Measure the perpendicular distance ‘b’ cm of P (lamp) from OX.Thus, the position of the table lamp P is described by the ordered pair (a, b).