# Polar Coordinates Question

• June 23rd 2010, 10:09 PM
NotoriousPi
Polar Coordinates Question (Solved)
Um, how would one convert this rectangular equation into polar form:

(x+1)^2 + (y-4)^2 = 17
• June 23rd 2010, 11:16 PM
red_dog
Put $x=\rho\cos\theta, \ y=\rho\sin\theta$. Then

$(\rho\cos\theta+1)^2+(\rho\sin\theta-4)^2=17$

$\rho^2(\cos^2\theta+\sin^2\theta)+2\rho\cos\theta-8\rho\sin\theta=0$

$\rho^2+2\rho(\cos\theta-4\sin\theta)=0$
• June 23rd 2010, 11:26 PM
NotoriousPi
Many thanks. I solved this problem differently, but I was checking to match up answers.
• June 24th 2010, 01:07 PM
HallsofIvy
Then you should have given the answer first and asked others to check it. Many people will not simply give you the answer to a home work problem.
• June 24th 2010, 05:47 PM
NotoriousPi
Well, it was actually to study before a test, but yes, if I do have similar problems, I will post up next time.