MHT CET2011MathematicsParabola
The equations of the normals at the ends of the latusrectum of the parabola y²=4 a x are given by
Options
- Ax²-y²-6 a x+9 a²=0
- Bx²-y²-6 a x-6 a y+9 a²=0
- Cx²-y²-6 a y+9 a²=0
- DNone of the above
Correct answer
A. x²-y²-6 a x+9 a²=0
Step-by-step solution
The coordinates of the ends of the latusrectum of the parabola y²=4 a x are (a, 2 a) respectively. The equation of the normal at (a, 2 a) to y²=4 a x is y-2 a= -2 a 2 a (x-a) or x+y-3 a=0 Similarly, the equation of the normal (a,-2 a) is x-y-3 a=0 The combined equation is x²-y²-6 a x+9 a²=0