Question

If one of the diameters of the circle $x^2 + y^2 - 2x - 6y + 6 = 0$ is a chord to the circle with centre (2,1), then the radius of the circle is

• A. $\sqrt3$
• B. $\sqrt2$
• C. 3
• D. 2

Answer 1

Answer: (C)

3

Answer 2

Here, radius of sm aller circle, AC = $\sqrt{1 + 9- 6} = 2$
Clearly, from the figure the radius of bigger circle
$r^2 = 2^2 + [(2 - 1)^2 + (1 - 3)^2]$
$r^2=9 \Rightarrow r = 3$