WBJEE · Maths · Circle
If the equation of one tangent to the circle with centre at \((2,-1)\) from the origin is \(3 x+y=0\), then the equation of the other tangent through the origin is
- A \(3 x-y=0\)
- B \(x+3 y=0\)
- C \(x-3 y=0\)
- D \(x+2 y=0\)
Answer & Solution
Correct Answer
(C) \(x-3 y=0\)
Step-by-step Solution
Detailed explanation
\[ \begin{aligned} &\because \mathrm{CA}=\mathrm{CB} \\ &\Rightarrow \frac{5}{\sqrt{10}}=\left|\frac{2 \mathrm{~m}+1}{\sqrt{1+\mathrm{m}^2}}\right| \end{aligned} \] squaring \[ \frac{25}{10}=\frac{4 m^2+4 m+1}{1+m^2} \]…
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