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WBJEE · Maths · Circle

If the coordinates of one end of a diameter of the circle \(x^2+y^2+4 x-8 y+5=0\), is \((2,1)\), the coordinates of the other end is

  1. A \((-6,-7)\)
  2. B \((6,7)\)
  3. C \((-6,7)\)
  4. D \((7,-6)\)
Verified Solution

Answer & Solution

Correct Answer

(C) \((-6,7)\)

Step-by-step Solution

Detailed explanation

Hints: \(x^2+y^2+9 x-8 y+5=0\) Centre circle \((-2,4)\) \(\begin{aligned} & \frac{\mathrm{h}+2}{2}=-2 \\ & \mathrm{~h}=-4-2=-6 \\ & \frac{\mathrm{k}+1}{2}=4 \Rightarrow \mathrm{k}=7 \\ & (\mathrm{~h}, \mathrm{k}) \rightarrow(-6,7) \end{aligned}\)