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General Equation of a circle with centre (a, b) and radius r
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(x − a)² + (y − b)² = r²
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Substitute (6,0) and r = 6
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(x - 6)² + (y - 0)² = 6²
(x - 6)² + y² = 36
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Answer: (x - 6)² + y² = 36 (Answer A)
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