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10-2. Parabola, Ellipse, Hyperbola
medium
Let the tangent drawn to the parabola $y ^{2}=24 x$ at the point $(\alpha, \beta)$ is perpendicular to the line $2 x$ $+2 y=5$. Then the normal to the hyperbola $\frac{x^{2}}{\alpha^{2}}-\frac{y^{2}}{\beta^{2}}=1$ at the point $(\alpha+4, \beta+4)$ does $NOT$ pass through the point.
A
$(25,10)$
B
$(20,12)$
C
$(30,8)$
D
$(15,13)$
(JEE MAIN-2022)
Solution
Tangent at $(\alpha, \beta)$ has slope 1
$\beta^{2}=24 \alpha$
Equation of tangent $y \beta=12(x+\alpha), \frac{12}{\beta}=1$
$\Rightarrow \alpha=6, \beta=12$
$\therefore(\alpha+4, \beta+4)=(10,16)$
Normal at $(10,16)$ to $\frac{x^{2}}{36}-\frac{y^{2}}{144}=1$ is
$2 x+5 y=100$
Standard 11
Mathematics