Polar coordinates are used for planes. Extending this system into three dimensions in the simplest way results in a cylindrical coordinate system. A cylindrical coordinate system uses the same r and as in polar coordinates, with an added dimension along to the z-axis. The three coordinates that define a point in a cylindrical coordinate system is the triple (r, , z). Consider a point in the three-dimensional Cartesian coordinate system, (3, −4, 6) cm. Dacia and Katarina compute the corresponding point in a cylindrical coordinate system, whose origin corresponds to the origin in the Cartesian system. Which point do they find?