Gujarati
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

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