Convert from Rectangular to Polar Coordinates on the TI83 Plus
You’re used to seeing points in the xyplane displayed in the (x, y) rectangular form. But when dealing with polar equations, you view these points in their polar form. To convert (x, y) from rectangular to polar form on the TI83 Plus graphing calculator:

Press [2nd][APPS] to access the Angle menu. (On the TI83, press [2nd]MATRX].)

Press [5] to select the
option.

Enter the point (x, y) and press [ENTER] to display r in the
polar form of the point.
To do so, enter the xcoordinate, press [.], enter the ycoordinate, press [ ) ], and then press [ENTER]. The value of r appears on the right of the screen.

Press [2nd][APPS][6] to select the
option from the Angle menu. (On the TI83, press [2nd][MATRX][6].)

Enter the point (x, y) and press [ENTER] to display
in the
polar form of the point.
will be in degrees if the calculator is in Degree mode, or it will be measured in radians if the calculator is in Radian mode.
Converting from rectangular to polar coordinates.