Gujarati
10-1.Circle and System of Circles
normal

Length of the tangent drawn from any point on the circle ${x^2} + {y^2} + 2gx + 2fy + {c_1} = 0$ to the circle ${x^2} + {y^2} + 2gx + 2fy + c = 0$ is

A

$\sqrt {{c_1} - c} $

B

$\sqrt {c - {c_1}} $

C

$\sqrt {{c_1} + c} $

D

None of these

Solution

(b) Suppose $({x_1},\;{y_1})$ be any point on first circle from which tangent is to be drawn, then

$x_1^2 + y_1^2 + 2g{x_1} + 2f{y_1} + {c_1} = 0$….$(i)$

and also length of tangent

$ = \sqrt {{S_2}} = \sqrt {x_1^2 + y_1^2 + 2g{x_1} + 2f{y_1} + c} $….$(ii)$

From $(i)$, we get $ (ii)$ as $\sqrt {c – {c_1}} $.

Standard 11
Mathematics

Similar Questions

Start a Free Trial Now

Confusing about what to choose? Our team will schedule a demo shortly.