AP EAMCET201921 Apr 2019Morning ShiftMathematicsParabolaActual
If the tangent drawn to the parabola y^2=4 x at (t^2, 2 t ) is the normal to the ellipse 4 x^2+5 y^2=20 at ( 5 , 2 ) , then
Options
- A5 t^4+4 t^2=1
- B5 t^4 + 100 t^2 =1
- Ct=
- D=t+1
Correct answer
A. 5 t^4+4 t^2=1
Step-by-step solution
Given, tangent to parabola y^2=4 x at (t^2, 2 t ) is y 2 t=2 (x+t^2 ) y t=x+t^2 Normal to the ellipse 4 x^2+5 y^2=20 or x^2 5 + y^2 4 =1 at ( 5 , 2 ) Slope of normal =5 y / 4 x= 5 2 Equation of line is y-2 = 5 2 (x- 5 ) By comparing Eqs. (i) and (ii), we get t=- 2 aligned 1 t & = 5 2 & = 2 5 t aligned From Eqs. (iii) and (iv), we get -2 t= 2 4+5 t^2 On squaring both sides, we get t^2 (4+5 t^2 )=1 5 t^4+4 t^2=1