The first thing you should know in this case is that the equation is written in a rectangular form. It can be written in polar form. To do this, you must make the following change of variables: x = r * cos (theta) We have then: r * cos (theta) = 5 r = 5 / cos (theta) r = 5 * sec (theta) Answer: The polar form is: r = 5 * sec (theta) Note: the equation was already written in rectangular form.