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QJEEM23Ma0a1e: JEE Main 2023 Mathematics - Class 11 JEEM23Ma0a1e Solution: Let the eccentricity of an ellipse x 2 a 2 + y 2 b 2 = 1 is…

Let the eccentricity of an ellipse x2a2+y2b2=1 is reciprocal to that of the hyperbola 2x2−2y2=1. If the ellipse intersects the hyperbola at right angles, then square of length of the latus-rectum of the ellipse is ___________.

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Equation of hyperbola is 2x2−2y2=12 x^2-2 y^2=1

⇒x21/2−y21/2=1\Rightarrow \frac{x^2}{1 / 2}-\frac{y^2}{1 / 2}=1

Here, a=ba=b

∴\therefore Eccentricity of rectangular hyperbola is 2\sqrt{2}

∴\therefore Eccentricity of ellipse is 12\frac{1}{\sqrt{2}}

Since, ellipse intersects the hyperbola at right angles

∴\therefore Ellipse and the hyperbola are confocal

∴\therefore Foci of hyperbola =(1,0)=(1,0)

⇒\Rightarrow Foci of ellipse, ae=1a e=1

⇒a(12)=1⇒a=2∴e2=1−b2a2⇒12=1−b22⇒b22=12⇒b2=1

∴\therefore Length of the latus rectum =2b2a=22=2=\frac{2 b^2}{a}=\frac{2}{\sqrt{2}}=\sqrt{2}

∴\therefore Square of length of the latus rectum =2=2

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