Cartesian (Rectangular) and Polar Co-Ordinates

Cartesian, or rectangular, and polar co-ordinates are discussed on their own Page, this Page only explains how to convert from one to the other. In the examples angles are in degrees but you can also work in radians - to find out how to change from working in degrees to radians go to the Working with Angles Page.

To convert from Cartesian (rectangular) to polar co-ordinates press the SHIFT key followed by the Pol key. This opens the brackets for you, and you enter the x and y values separated by a comma (use SHIFT first of course), then close the brackets and press =.

Remember that the result will almost always involve irrational numbers, which will mean you may get an answer involving two ten-digit numbers and you will have to use the blue scroll key arrows to see them all. Irrational numbers are explained on their own Page.

For example, if *x* = 5 and *y* = 4 you would enter Pol (5,4) and get the answer

r = 6.403123237, θ = 38.65980825, which you will round to 6.4 and 38.7 - but do not forget to put in degrees!

Ans stores only the value of *r,* which it gives exactly, as a surd.

To convert from polar to Cartesian co-ordinates do the same but use the Rec key instead, and Ans stores only *x*

You cannot use the Pol and Rec keys when you are in TABLE or STAT mode.

© Barry Gray May2018