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## Homework Statement

Replace the Cartesian equation with an equivalent polar equation.

##x^2 + (y - 18)^2 = 324##

a)##r = 36 sin θ##

b)##r^2 = 36 cos θ##

c)##r = 18 sin θ##

d)##r = 36 cos θ##

## Homework Equations

##x= r cos \theta ##

##y= r sin \theta ##

##x^2 + y^2 = r^2 ##

## The Attempt at a Solution

##x^2 + (y - 18)^2 = 324##

##x^2 + y^2 - 2*18*y + 18^2 = 324 ##

##x^2 + y^2 - 36 y =0##

##r^2 = 36 y##

Divide by r :

##r = 36 r sin \theta##

So , the answer is (a) .Right ?