Tangents are drawn from any point on the circle $x^2 + y^2 = R^2$ to the circle $x^2 + y^2 = r^2$. If the line joining the points of intersection of these tangents with the first circle also touch the second, then $R$ equals
$\sqrt{2} r$
$2r$
$\frac{{2r}}{{2 - \sqrt 3 }}$
$\frac{{4r}}{{3 - \sqrt 5 }}$
The point at which the normal to the circle ${x^2} + {y^2} + 4x + 6y - 39 = 0$ at the point $(2, 3)$ will meet the circle again, is
If the distances from the origin to the centres of the three circles ${x^2} + {y^2} - 2{\lambda _i}\,x = {c^2},(i = 1,\,2,\,3)$ are in $G. P.$, then the lengths of the tangents drawn to them from any point on the circle ${x^2} + {y^2} = {c^2}$ are in
Equation of the tangent to the circle ${x^2} + {y^2} = {a^2}$ which is perpendicular to the straight line $y = mx + c$ is
The line $y = x + c$will intersect the circle ${x^2} + {y^2} = 1$ in two coincident points, if
If the centre of a circle is $(-6, 8)$ and it passes through the origin, then equation to its tangent at the origin, is