A) A straight line
B) A Circle
C) A parabola
D) An ellipse
Correct Answer: B
Solution :
If the line \[lx+my-1=0\] touches the circle\[{{x}^{2}}+{{y}^{2}}={{a}^{2}}\], then applying the condition of tangency, we have \[\pm \frac{l.0+m.0-1}{\sqrt{{{l}^{2}}+{{m}^{2}}}}=a\] On squaring and simplifying, we get the required locus \[{{x}^{2}}+{{y}^{2}}=\frac{1}{{{a}^{2}}}\]. Hence it is a circle.You need to login to perform this action.
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