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10-1.Circle and System of Circles
hard
यदि वृत्त $x^{2}+y^{2}-16 x-20 y+164=r^{2}$ तथा $( x -4)^{2}+( y -7)^{2}=36$ दो भिन्न बिन्दुओं पर काटते हैं, तो
A
$0 < r < 1$
B
$1 < r < 11$
C
$r>11$
D
$r=11$
(JEE MAIN-2019)
Solution
${x^2} + {y^2} – 16x – 20y + 164 = {r^2}$
$A\left( {8,10} \right),{R_1} = r$
${\left( {x – 4} \right)^2} + {\left( {y – 7} \right)^2} = 36$
$B\left( {4,7,} \right),{R_2} = 6$
$\left| {{R_1} – {R_2}} \right| < AB < {R_1} + {R_2}$
$ \Rightarrow 1 < r < 11$
Standard 11
Mathematics