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10-1.Circle and System of Circles
normal
Two concentric circles are such that the smaller divides the larger into two regions of equal area. If the radius of the smaller circle is $2$ , then the length of the tangent from any point $' P '$ on the larger circle to the smaller circle is :
A
$1$
B
$\sqrt{2}$
C
$2$
D
none
Solution

$\pi \,\, r_1^2 = \pi \,\,r_2^2 – \pi \,\, r_1^2$
$\Rightarrow \,\,2 \, r_1^2 =r_2^2 \,\,\,\, \Rightarrow r_2 = \sqrt{2} r_1$
Note $P$ lies on the director circle of radius $r_1$
$\Rightarrow\,\, L = r_1 = 2\, cm $
Standard 11
Mathematics