JEE Main 2015 · 11 Apr · Shift 1 · Mathematics Q80

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MathematicsSingle correct+4 / -1Question 80 of 90

If a circle passing through the point (−1, 0) touches $y$ -axis at (0, 2), then the length of the chord of the circle along the $x$ -axis is :

\dfrac32

\dfrac52

Answer and worked solution

Official answer: C

The centre is $(h,2)$ with radius $|h|$ . Through $(-1,0)$ : $(1+h)^2+4=h^2$ , so $h=-\frac52$ . On the $x$ -axis, $\left(x+\frac52\right)^2=\frac{25}4-4=\frac94$ : the chord has length 3.

Topics:Equation of a circle

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JEE Main 2015 · 11 Apr · Shift 1, Mathematics question 80