Answer:
because he cleverly confuses the trolls until dawn
C
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The equation of a circle is: (x - h)² + (y - k)² = radius² where (h, k) is the center. Now just plug in your given information and simplify.
(x - 2)² + (y - 0)² = 9²
Your equation is:
(x - 2)² + y² = 81
