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10-1.Circle and System of Circles
easy
रेखा $lx + my + n = 0$, वृत्त ${x^2} + {y^2} = {a^2}$ की एक स्पर्श रेखा होगी यदि
A
${n^2}({l^2} + {m^2}) = {a^2}$
B
${a^2}({l^2} + {m^2}) = {n^2}$
C
$n(l + m)a$
D
$a(l + m) = n$
Solution
(b) रेखा $y = mx + c$ स्पर्श रेखा होगी यदि$c = \pm {\rm{ }}a\sqrt {1 + {m^2}} $ हो।
अब$lx + my + n = 0$ या $y = – \frac{l}{m}x – \frac{n}{m}$ स्पर्श रेखा होगी
यदि$ – \frac{n}{m} = \pm a\sqrt {1 + {{\left( {\frac{l}{m}} \right)}^2}} $ या ${n^2} = {a^2}({m^2} + {l^2})$.
Standard 11
Mathematics