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AP EAMCET · Maths · Pair of Lines

If the axes are rotated through an angle ' \(\alpha\) ', then the number of values of \(\alpha\) such that the transformed equation of \(x^2+y^2+2 x+2 y-5=0\) contains no linear terms is

  1. A \(0\)
  2. B \(1\)
  3. C \(2\)
  4. D infinite
Verified Solution

Answer & Solution

Correct Answer

(A) \(0\)

Step-by-step Solution

Detailed explanation

\begin{aligned} & \quad x^2+y^2+2 x+2 y-5=0 \\ & \text { Let } x=\mathrm{X} \cos \alpha-\mathrm{Y} \sin \alpha \text { and } y=\mathrm{X} \sin \alpha+\mathrm{Y} \cos \alpha \\ & \therefore(\mathrm{X} \cos \alpha-\mathrm{Y} \sin \alpha)^2+(\mathrm{X} \sin \alpha+\mathrm{Y} \cos…