JEE MainMathematicsParabola
A chord AB of the parabola y^2 = 12x passes through the focus S . The tangents to the parabola at A and B intersect at a point P . If both the tangents make an equal acute angle with the line 2x - y + 5 = 0 , then the value of 10 is:
Options
- A20
- B5
- C0
- D10
Correct answer
D. 10
Step-by-step solution
Since the chord AB passes through the focus S of the parabola y^2 = 12x , it is a focal chord. A known property of parabolas is that the tangents drawn at the extremities of a focal chord intersect at right angles on the directrix. Therefore, the angle between the tangent at A and the tangent at B is 90^ . We are given that both these perpendicular tangents make an equal acute angle with the line 2x - y + 5 = 0 . For a line to make equal acute angles with two mutually perpendicular lines, it must be parallel to one