How do you convert r=6/(2-cos(theta))r=62cos(θ) into cartesian form?

1 Answer
Nov 8, 2016

The cartesian form is 3x^2-12x+4y^2-36=03x212x+4y236=0

Explanation:

The formulae used are r^2=x^2+y^2r2=x2+y2
and x=rcosthetax=rcosθ and y=rsinthetay=rsinθ

Rewring the polar form as r(2-costheta)=6r(2cosθ)=6
Replacing costheta=x/rcosθ=xr
We get r(2-x/r)=6r(2xr)=6=>2r-x=62rx=6
=> 2r=x+62r=x+6
replacing rr
2sqrt(x^2+y^2)=x+62x2+y2=x+6
Squaring both sides
4(x^2+y^2)=(x+6)^24(x2+y2)=(x+6)2
4x^2+4y^2=x^2+12x+364x2+4y2=x2+12x+36
3x^2-12x+4y^2-36=03x212x+4y236=0
graph{3x^2-12x+4y^2-36=0 [-7.9, 7.9, -3.95, 3.95]}