What is the polar equation for $x^2+y^2=9$ ?

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Answer 1 · 2018-04-07T15:36:05

$x=3costheta$
$y=3sintheta$

the equation $y^2+x^2=9$ is an equation of a circle

it's radius is $3$ and it's center is $(0,0)$

and to find the the polar equation of a circle you use the following formula
$x=h+rcostheta$
$y=k+rsintheta$

where $(h,k)$ is the center of the circle which is in this case is $(0,0)$
and by substituting You get:
$x=3costheta$
$y=3sintheta$

What is the polar equation for x^2+y^2=9x^2+y^2=9?