Let O be the vertex of the parabola y2=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 :
(A)1
(B)2✓ Correct
(C)4
(D)8
Answer: (B)
Solution
Take P(t12,2t1) and Q(t22,2t2) on y2=4x. The chords OP and OQ have slopes t12 and t22, and perpendicularity gives t1t24=−1, so t1t2=−4. For the midpoint (h,k) of PQ,
k=t1+t2,2h=t12+t22=(t1+t2)2−2t1t2=k2+8.
Hence k2=2h−8=2(h−4), a parabola whose latus rectum has length 2.
JEE Main · 2026 · 08 Apr 2026 · Shift 2 · Single correct option