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AP EAMCET · Maths · Straight Lines

When the coordinate axes are rotated through an angle of \(45^{\circ}\) about the origin in the positive direction, if the transformed equation of a curve is \(17 x^2-16 x y+17 y^2=225\), then the original equation of that curve is

  1. A \(25 x^2+9 y^2=225\)
  2. B \(9 x^2-25 y^2=225\)
  3. C \(25 x^2-16 x y+9 y^2=225\)
  4. D \(9 x^2+25 y^2=225\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(25 x^2+9 y^2=225\)

Step-by-step Solution

Detailed explanation

When the axes are rotated through \(45^{\circ}\) about the origin in the positive direction then replace \((x, y)\) by \(\left(\frac{x}{\sqrt{2}}+\frac{y}{\sqrt{2}}, \frac{-x}{\sqrt{2}}+\frac{y}{\sqrt{2}}\right)\) So, original equation of the curve,…