Q.
The two circles
$x^{2} + y^{2} - 5 = 0$ and
$x^{2} + y^{2} - 2x - 4y - 15 = 0$
A) Touch each other externally
B) Touch each other internally
C) Cut each other orthogonally
D) Do not intersect
Explanation
(b)
Centre and radii of two circles are
$C_{1}(0,\ 0),\ C_{2}(1,\ 2)$ and $r_{1} = \sqrt{5},\ r_{2} = 2\sqrt{5}$
Since, $C_{1}C_{2} = \sqrt{5} = r_{2} - r_{1}$, therefore, the two circles touch each other internally
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.