PYQSide ExamsMy practice

Three Dimensional Geometry · Question 22

JEE Main 2026 (Online) 24th January Morning ShiftNumericalMedium📈 Topic in 35% papers+4
1

Let a line L passing through the point P(1, 1, 1) be perpendicular to the lines x-44 = y-11 = z-11 and x-171 = y-711 = z0. Let the line L intersect the yz-plane at the point Q. Another line parallel to L and passing through the point S(1, 0, -1) intersects the yz-plane at the point R. Then the square of the area of the parallelogram PQRS is equal to .

Answer

6

Solution

Direction of L both (4, 1, 1) and (1, 1, 0):

vmatrix i & j & k \ 4 & 1 & 1 \ 1 & 1 & 0 vmatrix = - i + j + 3 k

L: (1 - t, 1 + t, 1 + 3t); on the yz-plane x = 0 t = 1

Q = (0, 2, 4)

Line through S parallel to L: (1 - t, t, -1 + 3t); x = 0 t = 1

R = (0, 1, 2)

PQ = - i + j + 3 k, PS = - j - 2 k (and SR = PQ, so PQRS is a parallelogram)

PQ PS = vmatrix i & j & k \ -1 & 1 & 3 \ 0 & -1 & -2 vmatrix = i - 2 j + k

(Area)2 = | PQ PS|2 = 1 + 4 + 1 = 6

Answer: 6

JEE Main 2026 (Online) 24th January Morning Shift

Keep practising — Three Dimensional Geometry

2

The sum of all values of , for which the shortest distance between the lines x+1 = y-2-1 = z-4- and x = y-12 = z-12 is 2, is

  1. -6
  2. -8
  3. 8
  4. 6
JEE Main 2026 (Online) 24th January Evening Shift
3

Let the direction cosines of two lines satisfy the equations : 4l + m - n = 0 and 2mn + 10nl + 3lm = 0. Then the cosine of the acute angle between these lines is :

  1. 107 38
  2. 10 38
  3. 103 38
  4. 203 38
JEE Main 2026 (Online) 23rd January Morning Shift
4

The vertices B and C of a triangle ABC lie on the line x1 = 1 - y-2 = z - 23. The coordinates of A and B are (1, 6, 3) and (4, 9, α) respectively and C is at a distance of 10 units from B. The area (in sq. units) of ABC is :

  1. 20 13
  2. 5 13
  3. 15 13
  4. 10 13
JEE Main 2026 (Online) 23rd January Morning Shift
5

If the image of the point P(a, 2, a) in the line x2 = y + a1 = z1 is Q and the image of Q in the line x - 2b2 = y - a1 = z + 2b-5 is P , then a + b is equal to .

JEE Main 2026 (Online) 23rd January Evening Shift
6

Let P( , , ) be the point on the line x - 12 = y + 1-3 = z at a distance 4 14 from the point (1, -1, 0) and nearer to the origin. Then the shortest distance, between the lines x - 1 = y - 2 = z - 3 and x + 52 = y - 101 = z - 31, is equal to

  1. 4 75
  2. 7 54
  3. 4 57
  4. 2 74
JEE Main 2026 (Online) 22nd January Morning Shift
7

If the image of the point P(1, 2, a) in the line x - 63 = y - 72 = 7 - z2 is Q(5, b, c), then a2 + b2 + c2 is equal to

  1. 298
  2. 264
  3. 293
  4. 283
JEE Main 2026 (Online) 22nd January Morning Shift
8

Let L be the line x+12 = y+13 = z+36 and let S be the set of all points (a, b, c) on L, whose distance from the line x+12 = y+13 = z-90 along the line L is 7. Then (a, b, c) S (a + b + c) is equal to :

  1. 28
  2. 6
  3. 40
  4. 34
JEE Main 2026 (Online) 22nd January Evening Shift
9

Let ( , , ) be the co-ordinates of the foot of the perpendicular drawn from the point (5, 4, 2) on the line r = (- i + 3 j + k) + (2 i + 3 j - k). Then the length of the projection of the vector i + j + k on the vector 6 i + 2 j + 3 k is :

  1. 187
  2. 157
  3. 4
  4. 3
JEE Main 2026 (Online) 21st January Morning Shift
10

Let the line L pass through the point (-3, 5, 2) and make equal angles with the positive coordinate axes. If the distance of L from the point (-2, r, 1) is 143, then the sum of all possible values of r is :

  1. 16
  2. 12
  3. 6
  4. 10
JEE Main 2026 (Online) 21st January Evening Shift
11

Let the line L1 be parallel to the vector -3 i + 2 j + 4 k and pass through the point (2, 6, 7), and the line L2 be parallel to the vector 2 i + j + 3 k and pass through the point (4, 3, 5). If the line L3 is parallel to the vector -3 i + 5 j + 16 k and intersects the lines L1 and L2 at the points C and D, respectively, then | CD |2 is equal to:

  1. 290
  2. 171
  3. 89
  4. 312
JEE Main 2026 (Online) 21st January Evening Shift

All Three Dimensional Geometry PYQs →

PDFDownload Three Dimensional Geometry PYQs as PDF Free, with answer key and a QR code to every solution — print it or study offline⬇
All JEE Main Mathematics chapters