Hi, I need help converting r=2-cos(theta) into rectangular form. My teacher gave us the correct answer: 0=(x^4)+(2x^3)-(3x^2)+(2x^2)(y^2)+(xy)-(4y^2)+(y^4), but I don't know how to get there. I understand how to solve basic polar conversions but this problem was above my understanding. Thanks for any help!

This is as far as I got, but I don't even know if I started the problem correctly.