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Question
Find the equation of the circle with centre at (2, −3) and radius 5.
Solution
The equation of a circle with centre at (h, k) and radius ‘r’ is given by
(x – h)2 + (y – k)2 = r2
Here, h = 2, k = –3 and r = 5
∴ The required equation of the circle is
(x – 2)2 + [y – (–3)]2 = 52
∴ (x – 2)2 + (y + 3)2 = 25
∴ x2 – 4x + 4 + y2 + 6y + 9 – 25 = 0
∴ x2 + y2 – 4x + 6y – 12 = 0
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