Manipal MET2010MathematicsParabola
If the normal to the parabola y^2=4 a x at the point (a t^2, 2 a t ) cuts the parabola again at (a T^2, 2 a T ) , then
Options
- A-2 T 2
- BT (- ,-8) (8, )
- CT^2 8
- DT^2 8
Correct answer
D. T^2 8
Step-by-step solution
Equation of the normal of the parabola y^2=4 a x at the point (a t^2, 2 a t ) is y+t x=2 a t+a t^3...(i) Eq. (i) cuts the parabola again at (a T^2, 2 a T ) . Then, 2 a T+t a T^2=2 a t+a t^3 2 a(T-t)=-a t (T^2-t^2 ) 2=-t(T+t) ( t T) t^2+t T+2=0 t is real, T^2-4 1 2 0 T^2 8