Gujarati
10-1.Circle and System of Circles
easy

रेखा $y = 2x + c$ को वृत्त ${x^2} + {y^2} = 16$ की स्पर्श रेखा होने के लिए $c$ का मान है

A

$ - 16\sqrt 5 $

B

$20$

C

$4\sqrt 5 $

D

$16\sqrt 5 $

Solution

(c) $c =  \pm a\sqrt {1 + {m^2}} $ से,

यहाँ, $a = 4,\,m = 2$

$\therefore \,c =  \pm {\rm{  }}4\sqrt {1 + 4} $

$=  \pm {\rm{  }}4\sqrt 5 $.

Standard 11
Mathematics

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