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Question
Find the equation of the circle concentric with x2 + y2 − 4x − 6y − 3 = 0 and which touches the y-axis.
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Solution
Since, the circles are concentric.
We know that if a circle with centre (h, k) touches the y-axis, then h is the radius of the circle.
Thus, the radius is 2.
∴ Equation of the circle: \[\left( x - 2 \right)^2 + \left( y - 3 \right)^2 = 2^2\]
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