Let A (sec$\theta$, 2tan$\theta$) and B (sec$\phi$, 2tan$\phi$), where $\theta$ + $\phi$ = $\pi$/2, be two points on the hyperbola 2x2 $-$ y2 = 2. If ($\alpha$, $\beta$) is the point of the intersection of the normals to the hyperbola at A and B, then (2$\beta$)2 is equal to ____________.
Solution
Since, point A (sec$\theta$, 2tan$\theta$) lies on the hyperbola 2x<sup>2</sup> $-$ y<sup>2</sup> = 2<br><br>Therefore, 2sec<sup>2</sup>$\theta$ $-$ 4tan<sup>2</sup>$\theta$ = 2<br><br>$\Rightarrow$ 2 + 2tan<sup>2</sup>$\theta$ $-$ 4tan<sup>2</sup>$\theta$ = 2<br><br>$\Rightarrow$ tan$\theta$ = 0 $\Rightarrow$ $\theta$ = 0<br><br>Similarly, for point B, we will get $\phi$ = 0.<br><br>but according to question $\theta$ + $\phi$ = ${\pi \over 2}$ which is not possible.<br><br>Hence, it must be a 'BONUS'.
About this question
Subject: Mathematics · Chapter: Conic Sections · Topic: Parabola
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