# Math Help - Polar form

1. ## Polar form

Convert the equation to polar form..... Plz explain
#1 x^2+y^2=9

#2 y=5

Convert the polar to rectangular coordinates

#3 r^2=sin2(theta)

#4 r=1/(1+sin(theta))

2. Use the following to convert:

Polar to rectangular:
$x = r\cos \theta$
$y = r\sin \theta$

Rectangular to polar:
$r = \sqrt{x^2 + y^2}$
$\theta = \tan^{-1} \left(\frac{y}{x}\right)$

So...
#1:
$x^2 + y^2 = 9$
$r^2 = 9$
$r = 3$

01

3. I got it to R=3 im not sure what to do from there or is that it?