Circle And System Of Circles Question 294

Question: A circle passes through (0, 0) and (1, 0) and touches the circle $ x^{2}+y^{2}=9 $ , then the centre of circle is

[IIT 1992]

Options:

A) $ ( \frac{3}{2},\frac{1}{2} ) $

B) $ ( \frac{1}{2},\frac{3}{2} ) $

C) $ ( \frac{1}{2},\frac{1}{2} ) $

D) $ ( \frac{1}{2},\ \pm \sqrt{2} ) $

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Answer:

Correct Answer: D

Solution:

Radius of the circle $ r=\frac{3}{2} $

$ \frac{1}{4}+k^{2}=\frac{9}{4}\Rightarrow k=\pm \sqrt{2} $

Hence centre is $ ( \frac{1}{2},\ \pm \sqrt{2} ) $ .