The points of intersection of circles ${x^2} + {y^2} = 2ax$ and ${x^2} + {y^2} = 2by$ are
$(0, 0)$, $(a, b)$
$(0, 0)$, $\left( {\frac{{2a{b^2}}}{{{a^2} + {b^2}}},\frac{{2b{a^2}}}{{{a^2} + {b^2}}}} \right)$
$(0, 0)$, $\left( {\frac{{{a^2} + {b^2}}}{{{a^2}}},\frac{{{a^2} + {b^2}}}{{{b^2}}}} \right)$
None of the above
Give the number of common tangents to circle ${x^2} + {y^2} + 2x + 8y - 23 = 0$ and ${x^2} + {y^2} - 4x - 10y + 9 = 0$
The two circles ${x^2} + {y^2} - 2x - 3 = 0$ and ${x^2} + {y^2} - 4x - 6y - 8 = 0$ are such that
If the circles ${x^2} + {y^2} = 4,{x^2} + {y^2} - 10x + \lambda = 0$ touch externally, then $\lambda $ is equal to
The circles $x^2 + y^2 + 2x -2y + 1 = 0$ and $x^2 + y^2 -2x -2y + 1 = 0$ touch each other :-
Two circles of radii $4$ cms $\&\,\, 1\,\, cm$ touch each other externally and $\theta$ is the angle contained by their direct common tangents. Then $sin \theta =$