Q. The equation of normal to the circle ${2x}^{2} + {2y}^{2} - 2x - 5y + 3 = 0$ at (1, 1) is

A) $2x + y = 3$
B) $x - 2y = 3$
C) $x + 2y = 3$
D) None of these
Explanation

(c)
The equation of tangent to the given circle $2x^{2} + 2y^{2} - 2x - 5y + 3 = 0$ at point (1, 1) is
$2x + 2y - (x + 1) - \frac{5}{2}(y + 1) + 3 = 0$
$\Rightarrow x - \frac{1}{2}y - \frac{1}{2} = 0$
$\Rightarrow 2x - y - 1 = 0$
$\Rightarrow y = 2x - 1$
Slope of tangent=2, therefore slope of normal $= - \frac{1}{2}$
Hence, equation of normal at point (1, 1) and having slope $\left( - \frac{1}{2} \right)$ is
$y - 1 = - \frac{1}{2}(x - 1)$
$\Rightarrow 2y - 2 = - x + 1$
$\Rightarrow x + 2y = 3$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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