Circle Ques 7
- The lines $3 x-4 y+4=0$ and $6 x-8 y-7=0$ tangents to the same circle. The radius of this circle is…
(1984, 2M)
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Answer:
Correct Answer: 7.($\frac {3}{4}$)
Solution:
Formula:
- Since, $3 x-4 y+4=0$ and $3 x-4 y-\frac{7}{2}=0$ are two parallel tangents. Thus, distance between them is twice the radius of the circle
$ \begin{array}{rlrl} \Rightarrow & & \text { Diameter } & =\frac{\left|4+\frac{7}{2}\right|}{\sqrt{3^{2}+4^{2}}}=\frac{15}{5}=\frac{3}{1} \\ \text { and } & \text { radius } & =\frac{4}{3} \end{array} $
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