AP EAMCET202124 Aug 2021Evening ShiftMathematicsStraight LinesActual
Find the transformed equation of the curve x^2+2 3 x y-y^2=8 , when the axes are rotated through an angle 3 .
Options
- Ax^2+y^2+2 3 x y=8
- Bx^2+y^2-2 3 x y=8
- Cx^2-y^2+2 3 x y=8
- Dx^2-y^2-2 3 x y=8
Correct answer
D. x^2-y^2-2 3 x y=8
Step-by-step solution
Given equation, x^2+2 3 x y-y^2=8 Since, the axes are rotated through an angle / 3 . (x, y) replaced by (x 3 -y 3 , x 3 +y 3 ) i.e. ( x- 3 y 2 , 3 x+y 2 ) in the given equation. ( x- 3 y 2 )^2+2 3 ( x- 3 y 2 ) ( 3 x+y 2 )- ( 3 x+y 2 )^2=8 aligned 1 4 (x^2-2 3 x y . & +3 y^2+6 x^2-4 3 x y & .-6 y^2-3 x^2-2 3 x-y^2 )=8 aligned 1 4 (4 x^2-8 3 x y-4 y^2 )=8 x^2-2 3 x y-y^2=8