= y and OC = z . Then, the point P will have the coordinates x , y and z and we write P ( x , y , z ). Conversely, given x , y and z , we locate the three points A, B and C on the three coordinate axes. Through the points A, B and C we draw planes parallel to the YZ-plane, ZX-plane and XY-plane, respectively.
The point of interesection of these three planes, namely, ADPF, BDPE and CEPF is obviously the point P, corresponding to the ordered triplet ( x , y , z ). We observe that if P ( x , y , z ) is any point in the space, then x , y and z are perpendicular distances from YZ, ZX and XY planes, respectively.