Question

If P, Q, R are three points on a parabola y2 = 4ax whose ordinates are in geometrical progression, then the tangents at and R meet on

Solution

Correct option is

The line through Q parallel to y-axis

Let the coordinates of P, Q, R be (ati2, 2ati)i = 1, 2, 3 having ordinates in G.P. So that t1t2t3 are also in G.P. i.e. t1t3 = t22. Equations of the tangents at P and R are

ty = x + at12 and t3 y = x + at32, which intersect at the point

Which is a line through Q parallel to y-axis.

SIMILAR QUESTIONS

Q1

A point P moves such that the difference between its distance from the origin and from the axis of x is always a constant c. the locus of P is a

Q2

Shortest distance of the point (0, c) from the parabola y = x2where  is

Q3

The length of the intercept on the normal at the point (at2, 2at) of the parabola y2 = 4ax made by the circle which is described on the focal distance of the given point as diameter is 

Q4

A line bisecting the ordinate PN of a point P(at2, 2at), t > 0, on the parabola y2 = 4ax is drawn parallel to the axis to meet the curve at Q. If NQ meets the tangent at the vertex at the point T, then the coordinates of T are.

Q5

If Land L2 are the length of the segments of any focal chord of the parabola y2 = x, then  is equal to

Q6

The tangents at three points A, B, C on the parabola y2 = 4x, taken in pairs intersect at the points Pand R. If  be the areas of the triangles ABC and PQR respectively, then 

Q7

The locus of the mid-point of the line segment joining the focus to a moving point on the parabola y2 = 4ax is another parabola with directrix

Q8

Equation of a common tangent to the curves y2 = 8x and xy = –1 is