Question

The tangents at the end of any focal chord to the parabola $y^2=12x$ intersect on the line

• A. $x-3=0$
• B. $y+3=0$
• C. $x+3=0$
• D. $y-3=0$

Answer 1

The correct option is C $x+3=0$

The tangent at the end of any focal chord to the parabola intersect on the directrix.

The equation of the parabola is $y^2=12x$

$y^2=4\times 3x$ is of the form $y^2=4ax$

$\Rightarrow a=3$

The equation of the directrix is

$x=-3$

or $x+3=0$