# Rectangular into polar form

• December 15th 2008, 08:27 PM
cmr7
Rectangular into polar form
How about x^2 + 2xy + y^2 =9

Can someone show me this step by step?

Thank you so much,
Caleb
• December 15th 2008, 08:30 PM
mr fantastic
Quote:

Originally Posted by cmr7
How about x^2 + 2xy + y^2 =9

Can someone show me this step by step?

Thank you so much,
Caleb

Substitute $x = r \cos \theta$ and $y = r \sin \theta$ and simplify. Note that $x^2 + y^2 = r^2$.
• December 15th 2008, 08:31 PM
cmr7
Thank You Mr. Fantastic!!