Find a polar equation for the circle.
-$$( x + 9 ) ^ { 2 } + y ^ { 2 } = 81$$
A) $r \cos \theta = - 18$
B) $r = - 18 \sin \theta$
C) $\mathrm { r } = 18 \cos \theta$
D) $r = - 18 \cos \theta$

Question

Quizplus · Accepted Answer

The given equation is a circle centered at (-9, 0) with a radius of 9. In polar coordinates, this translates to $r \cos \theta = -9$, which simplifies to $r = -18 \cos \theta$.

Find a Polar Equation for the Circle (x+9)2+y2=81( x + 9 ) ^ { 2 } + y ^ { 2 } = 81(x+9)2+y2=81

Find a Polar Equation for the Circle $( x + 9 ) ^ { 2 } + y ^ { 2 } = 81$