X^2+y^2 = 16
can be written as
(x-0)^2+(y-0)^2 = 4^2
We see that the second equation is in the form
(x-h)^2 + (y-k)^2 = r^2
where
(h,k) = (0,0) is the center
r = 4 is the radius
The polar form of the equation is simply r = 4. Why is this? Because the radius is fixed to be 4 no matter what happens with theta. As theta goes from 0 to 360, the points generated all form a circle centered at (0,0) with radius 4.
Answer: r = 4
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