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← JEE Main 2022 · 29 Jun · Shift 1
MathematicsInteger+4 / -1Question 23 of 90

JEE Main 2022 · 29 Jun · Shift 1, Mathematics question 23

Let d be the distance between the foot of perpendiculars of the points P(1,2,−1)P(1,2,-1) and Q(2,−1,3)Q(2,-1,3) on the plane −x+y+z=1-x+y+z=1. Then d2d^2 is equal to ______.

Answer and worked solution

Official answer: 26

PQ =(1,−3,4)=(1,-3,4) is parallel to the plane (PQ⃗⋅(−1,1,1)=0\vec{PQ}\cdot(-1,1,1)=0), so the feet are as far apart as P and Q.

d2=1+9+16=26d^2=1+9+16=26.

Answer: 26