Gujarati
10-1.Circle and System of Circles
hard

बिन्दु $(0, 1)$ से वृत्त ${x^2} + {y^2} - 2x + 4y = 0$ पर खींची गयी स्पर्श रेखाओं के समीकरण हैं

A

$2x - y + 1 = 0,\,\,x + 2y - 2 = 0$

B

$2x - y + 1 = 0,\,\,x + 2y + 2 = 0$

C

$2x - y - 1 = 0,\,\,x + 2y - 2 = 0$

D

$2x - y - 1 = 0,\,\,x + 2y + 2 = 0$

Solution

(a)अभीष्ट समीकरण $S{S_1} = {T^2}$ द्वारा दिये जाते हैं।

$ \Rightarrow ({x^2} + {y^2} – 2x + 4y)(1 + 4) $

$= {\{ y – 1(x) + 2(y + 1)\} ^2}$

$ \Rightarrow 2{x^2} – 2{y^2} – 3x + 4y + 3xy – 2 = 0$

$ \Rightarrow (2x – y + 1)(x + 2y – 2) = 0$.

Standard 11
Mathematics

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