Engineering
Mathematics
Distance from a Plane
Equation of Straight Line in 3D and Distance Of a Point From Line
Question

If the line x−23=y+12=z−1−1  intersects the plane 2x + 3y – z + 13 = 0 at a point P and the plane 3x + y + 4z = 16 at a point Q, then PQ is equal to

27

14

14

214

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Solution

x−23=y+12=z−1−1=λ

x = 3λ + 2, y = 2λ = 1, z = –λ + 1

Intersection with plane 2x + 3y – z + 13 = 0

2(3λ + 2) + 3(2λ –1)  (-λ + 1) + 13 = 0

13λ + 13 = 0

λ = –1

∴ P(–1, – 3, 2)

Intersection with plane

3x + y + 4z = 16

3(3λ + 2) + (2λ – 1) +4(–λ + 1) = 16

λ = 1

Q(5, 1,0)

PQ=62+42+22=56=214