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10-1.Circle and System of Circles
medium
यदि वृत्त ${x^2} + {y^2} = 4,{x^2} + {y^2} - 10x + \lambda = 0$ एक-दूसरे को बाह्यत: स्पर्श करते हैं, तब $\lambda $ का मान है
A
$-16$
B
$9$
C
$16$
D
$25$
Solution
(a) वृत्त $x_2 + y_2 = 4, x_2 + y_2 -10x + l = 0$ एक दूसरे को बाह्यत: स्पर्श करते हैं
${C_1}{C_2} = {r_1} + {r_2}$
${C_1}(0,\,0)$ व ${C_2} = (5,\,0)$
${r_1} = 2$ व ${r_2} = \sqrt {25 + \lambda } $
$\sqrt {{{(5 – 0)}^2} + 0} = 2 + \sqrt {25 + \lambda } $
$5 – 2 = \sqrt {25 + \lambda } $
$3 = \sqrt {25 + \lambda } $
$9 = 25 + \lambda $
$l = -16.$
Standard 11
Mathematics