Question 181 of 183MediumMCQ
Let the ellipse E1:a2x2+b2y2=1, a>b and E2:A2x2+B2y2=1
Solutions · 1
Official solution
\[\begin{aligned}
&\begin{aligned}
& 2 \mathrm{ae}=4 \\
& 2 \mathrm{a}\left(\frac{1}{\sqrt{3}}\right)=4 \\
& \Rightarrow \mathrm{a}=2 \sqrt{3} \\
& \Rightarrow 1-\frac{\mathrm{b}^2}{12}=\frac{1}{3} \Rightarrow \mathrm{~b}^2=8 \\
& \text { Now } \frac{2 \mathrm{~b}^2}{\mathrm{a}} \cdot \frac{2 \mathrm{~A}^2}{\mathrm{~B}}=\frac{32}{\sqrt{3}} \Rightarrow 2\left(\frac{8}{2 \sqrt{3}}\right) \frac{2 \mathrm{~A}^2}{\mathrm{~B}}=\frac{32}{\sqrt{3}} \\
& \Rightarrow \mathrm{~A}^2=2 \mathrm{~B} \\
& 1-\frac{\mathrm{A}^2}{\mathrm{~B}^2}=\frac{1}{3} \Rightarrow 1-\frac{2 \mathrm{~B}}{\mathrm{~B}^2}=\frac{1}{3} \Rightarrow \mathrm{~B}=3 \\
& \Rightarrow \mathrm{~A}^2=6 \\
& \frac{\mathrm{x}^2}{12}+\frac{\mathrm{y}^2}{8}=1 \ldots . .(1) \\
& \frac{\mathrm{x}^2}{6}+\frac{\mathrm{y}^2}{9}=1 \ldots . .(2)
\end{aligned}\\
\&\text { On solving (1) \& (2) we get }
\end{aligned}\]
\[(x,y)≡(56,56),(5−6,56),(56,5−6),(5−6,5−6) The four points are vertices of rectangle and its area =5246\]
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