JEE Mains · Maths · STD 11 - 10.1 circle and system of circle
The line \(2 x - y +1=0\) is a tangent to the circle at the point \((2,5)\) and the centre of the circle lies on \(x-2 y=4\). Then, the radius of the circle is
- A \(3 \sqrt{5}\)
- B \(5 \sqrt{3}\)
- C \(5 \sqrt{4}\)
- D \(4 \sqrt{5}\)
Answer & Solution
Correct Answer
(A) \(3 \sqrt{5}\)
Step-by-step Solution
Detailed explanation
\(\left(\frac{h-\frac{(h-4)}{2}}{2-h}\right)(2)=-1\) \(h=8\) center \((8,2)\) Radius \(\left.=\sqrt{(8-2)^{2}+(2-5)^{2}}=3 \sqrt{5}\right)\)
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