41. A point in the complex plane can be represented by a complex number written in polar coordinates . 42. Sensors operate using a polar coordinate system. 43. The radar uses a polar coordinate system. 44. A handful of machines use polar coordinates instead, usually machines optimised to print objects with circular symmetry. 45. This is the equation in polar coordinates for a conic section with origin in a focal point. 46. There are various accounts of the introduction of polar coordinates as part of a formal coordinate system. 47. In cylindrical coordinates on the sphere and polar coordinates on the plane, the projection and its inverse are 48. The integrals over the two disks can easily be computed by switching from cartesian coordinates to polar coordinates : 49. In 1893 Durand published a paper mathematically describing a radial planimeter for averaging values plotted in polar coordinates . 50. For example, in polar coordinates :
