10-1.Circle and System of Circles
hard

माना कि रेखाऐं $y +2 x =\sqrt{11}+7 \sqrt{7}$ तथा $2 y + x =2$ lsqrt $\{11\}+6$ lsqrt 7 वृत $C 🙁 x - h )^2+( y - k )^2= r ^2$ का अभिलम्ब है। यदि रेखा $\sqrt{11} y -3 x =\frac{5 \sqrt{77}}{3}+11$, वृत $C$ पर स्पर्श रेखा है, तब $(5 h -8 k )^2+5 r ^2$ का मान बराबर है $.............$

A

$916$

B

$816$

C

$856$

D

$86$

(JEE MAIN-2022)

Solution

Normal are

$y +2 x =\sqrt{11}+7 \sqrt{7}$

$2 y + x =2 \sqrt{11}+6 \sqrt{7}$

Center of the circle is point of intersection of ormals i.e.

$\left(\frac{8 \sqrt{7}}{3}, \sqrt{11}+\frac{5 \sqrt{7}}{3}\right)$

Tangent is $\sqrt{11} y-3 x=\frac{5 \sqrt{77}}{3}+11$

Radius will be $\perp$ distance of tangent from center

i.e. $4 \sqrt{\frac{7}{5}}$

Now $(5 h -8 k )^{2}+5 r ^{2}=816$

Standard 11
Mathematics

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