Question

Write r=-12 cos θ in rectangular form. How to I go about rewriting this?

Answer 1

Think of a right triangle whose hypotenuse has length r and angle theta. The side adjacent to that angle, call it x, is the product of the hypotenuse and the cosine of theta. With this relationship and the polar expression you have been given you can now write and expression for x in terms of theta. And now you have enough facts to write an expression for the other side of the triangle, y.

Answer 2

Soooo x² + y² + 12x = 0 ???

Answer 3

Yup, very good!