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← JEE Main 2026 · 8 Apr · Shift 2
MathematicsSingle correct+4 / -1Question 11 of 75

JEE Main 2026 · 8 Apr · Shift 2, Mathematics question 11

Let O be the vertex of the parabola y2=4xy^2=4x and its chords OP and OQ are perpendicular to each other. If the locus of the mid-point of the line segment PQ is a conic C, then the length of its latus rectum is :

Choose one option
Answer and worked solution

Official answer: B

Perpendicular chords. With P(t12,2t1)P(t_1^2,2t_1) and Q(t22,2t2)Q(t_2^2,2t_2), OP⊥OQOP\perp OQ gives t1t2=−4t_1t_2=-4.

Midpoint. x=t12+t222x=\tfrac{t_1^2+t_2^2}2, y=t1+t2y=t_1+t_2, so
y2=t12+t22+2t1t2=2x−8.y^2=t_1^2+t_2^2+2t_1t_2=2x-8.

Conic. y2=2(x−4)y^2=2(x-4), with latus rectum 2.

(B)