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AP EAMCET · Maths · Ellipse

If a tangent of slope 2 to the ellipse \(\frac{x^2}{a^2}+\frac{y^2}{b^2}=1\) touches the circle \(x^2+y^2=4\), then maximum value of \(a b\) is

  1. A 4
  2. B 12
  3. C 5
  4. D 7
Verified Solution

Answer & Solution

Correct Answer

(C) 5

Step-by-step Solution

Detailed explanation

Given the ellipse, \(\frac{x^2}{a^2}+\frac{y^2}{b^2}=1\) Since, tangent to the given ellipse with slope \(m=2\) is given as \(y=m x \pm \sqrt{a^2 m^2+b^2} \Rightarrow y=2 x \pm \sqrt{4 a^2+b^2}\) \(\because\) it touches the circle \(x^2+y^2=4\) So,…