question_answer

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 : [JEE Main Online Paper (Held On 11 April 2015)]  

A) \[\frac{3}{2}\]

B) \[\frac{5}{2}\]

C)  3

D)  5

Correct Answer: B

Solution :

AM = r - 1 \[\therefore \]Using pythogoras theorem is \[\Delta CAM\] \[{{2}^{2}}+{{\left( r-1 \right)}^{2}}={{r}^{2}}\] \[\Rightarrow \]\[4+{{r}^{2}}-2r+1={{r}^{2}}\] \[\Rightarrow \]\[4+{{r}^{2}}-2r+1={{r}^{2}}\]\[\Rightarrow \]\[r={}^{5}/{}_{2}\]\[\Rightarrow \]