1.

The locus of the point of intersection of perpendicular tangents to a parabola is the directrix of the parabola. This locus is called director circle even though it is a line.

Answer»

The line

y = mx + a/m and y = -x/m - am

are tangents to the parabola and they intersect at right angles. Their point of intersection satisfies the equation 

x(m + 1/m) = -a(m + 1/m)

Hence, the locus of the point of intersection is the line x −a which is the directrix.



Discussion

No Comment Found

Related InterviewSolutions