The eccentricity of a rectangular hyperbola is

The eccentricity of a rectangular hyperbola is
  1. 2
  2. $2 \sqrt{2}$
  3. 1
  4. $\sqrt{2}$

Solution

The general equation of a hyperbola is \(\frac{x^2}{a^2}-\frac{y^2}{b^2}=1\), where \(a\) represents the transverse of hyperbola and \(b\) represents the conjugate of the hyperbola.
The eccentricity of a hyperbola is \(e=\frac{\sqrt{a^2+b^2}}{a} \cdots(1)\).
Since a rectangular hyperbola is defined as a hyperbola whose transverse axis is identical to its conjugate axis, \(a=b\).
Substitute \(a=b\) into (1).
\(\begin{aligned}
& e=\frac{\sqrt{a^2+b^2}}{a} \\
& \Rightarrow e=\frac{\sqrt{a^2+a^2}}{a} \\
& \Rightarrow e=\frac{\sqrt{2 a^2}}{a} \\
& \Rightarrow e=\frac{\sqrt{2} a}{a} \\
& \Rightarrow e=\sqrt{2}
\end{aligned}\)

Asked in: MHT CET 2020 (19 Oct Shift 1)

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