Polar and cartesian coordinates

[lmannoia]

Homework Statement

Write the following polar equation in Cartesian coordinates:
r= 2/(3cos(theta)-9sin(theta))

Homework Equations

r = (x^2 + y^2) ^.5
x=rcos theta
y=rsin theta
sin^2(x)+cos^2(x) = 1

The Attempt at a Solution

I'm stuck on how to do this. Any push in the right direction would be appreciated greatly!

 

[HallsofIvy]

Clear that fraction by multiplying both sides by 3cos(theta)- 9sin(theta) to get
r(3cos(theta)- 9sin(theta))= 3 (r cos(theta))- 9(r sin(theta))= 2.

Now it should be obvious.

 

[lmannoia]

Wow, I can't believe that I didn't see that. Thanks a lot!