Home Maths Conic Sections General Through the vertex 'O' of the parabola y 2 =…
Maths Conic Sections General Single Correct MCQ
Published on: August 13, 2026

Through the vertex 'O' of the parabola y 2 = 4ax, variable chords OP and OQ are drawn at right angles. If the variable chord PQ intersects the axis of x at R, then the distance OR is equal to

A
2a
B
3a
C
4a
D
8a

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Text Solution

Verified by Experts
The correct answer is:
C

Let the equation of line PQ be y = mx + c

by homogenization

y 2 = 4ax ⇒ y 2 + = 0

It is the equation of ⊥ r lines passing through 0(0, 0), then coefficient of x 2 + coefficient of y 2 = 0

Hence 1 + = 0 ⇒ = – .........(1)

y = mx + c cuts the x-axis

at R ⇒ OR = – = 4a [from (i)]

Hence OR = 4a = Latus Rectum

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