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Three Dimensional Geometry · Question 28

JEE Main 2026 (Online) 22nd January Morning ShiftMCQMedium📈 Topic in 68% papers+4−1
1

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

Answer

(1) 298

Solution

Line: x - 63 = y - 72 = z - 7-2 = t; direction ratios (3, 2, -2)

Mid-point M of PQ: (3, 2 + b2, a + c2 ) lies on the line

3 - 63 = t t = -1

M = (6 - 3, 7 - 2, 7 + 2) = (3, 5, 9)

2 + b2 = 5, a + c2 = 9

b = 8, a + c = 18

PQ is perpendicular to the line: PQ = (4, b - 2, c - a) = (4, 6, c - a)

3(4) + 2(6) - 2(c - a) = 0

c - a = 12

c = 15, a = 3

a2 + b2 + c2 = 9 + 64 + 225 = 298

Answer: (1)

JEE Main 2026 (Online) 22nd January Morning Shift

Keep practising — Three Dimensional Geometry

2

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
3

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
4

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
5

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
6

Let the values of for which the shortest distance between the lines x-12 = y-23 = z-34 and x- 3 = y-44 = z-55 is 1 6 be 1 and 2. Then the radius of the circle passing through the points (0, 0), ( 1, 2) and ( 2, 1) is

  1. 3
  2. 5 23
  3. 23
  4. 4
JEE Main 2025 (Online) 8th April Evening Shift
7

Let the area of the triangle formed by the lines x + 2 = y - 1 = z, x - 35 = y-1 = z - 11 and x-3 = y - 33 = z - 21 be A. Then A2 is equal to .

JEE Main 2025 (Online) 8th April Evening Shift
8

Let the line L pass through (1, 1, 1) and intersect the lines x-12 = y+13 = z-14 and x-31 = y-42 = z1. Then, which of the following points lies on the line L?

  1. (7, 15, 13)
  2. (4, 22, 7)
  3. (10, -29, -50)
  4. (5, 4, 3)
JEE Main 2025 (Online) 7th April Morning Shift
9

If the shortest distance between the lines x-12 = y-23 = z-34 and x1 = y = z-51 is 5 6, then the sum of all possible values of is

  1. 32
  2. 3
  3. -3
  4. - 32
JEE Main 2025 (Online) 7th April Morning Shift
10

If the equation of the line passing through the point (0, - 12, 0 ) and perpendicular to the lines r = ( i + a j + b k ) and r = ( i - j - 6 k ) + (-b i + a j + 5 k ) is x-1-2 = y+4d = z-c-4, then a + b + c + d is equal to :

  1. 13
  2. 14
  3. 12
  4. 10
JEE Main 2025 (Online) 7th April Evening Shift
11

Consider the lines L1: x - 1 = y - 2 = z and L2: x - 2 = y = z - 1. Let the feet of the perpendiculars from the point P(5, 1, -3) on the lines L1 and L2 be Q and R respectively. If the area of the triangle PQR is A, then 4A2 is equal to :

  1. 151
  2. 147
  3. 139
  4. 143
JEE Main 2025 (Online) 7th April Evening Shift

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