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Three Dimensional Geometry · Question 40

JEE Main 2025 (Online) 4th April Morning ShiftMCQMedium📈 Topic in 68% papers+4−1
1

Let A and B be two distinct points on the line L : x - 63 = y - 72 = z - 7-2. Both A and B are at a distance 2 17 from the foot of perpendicular drawn from the point (1, 2, 3) on the line L. If O is the origin, then OA OB is equal to

  1. 49
  2. 21
  3. 47
  4. 62

Answer

(3) 47

Solution

Any point of L: (6 + 3t, 7 + 2t, 7 - 2t); direction ratios of L: (3, 2, -2).

Let F be the foot of the perpendicular from (1, 2, 3). Then

(5 + 3t, 5 + 2t, 4 - 2t) (3, 2, -2) = 0

15 + 9t + 10 + 4t - 8 + 4t = 0

17 + 17t = 0 t = -1

F = (3, 5, 9)

Unit vector along L: (3, 2, -2) 17, so points at distance 2 17 from F are

F 2(3, 2, -2)

A = (9, 9, 5), B = (-3, 1, 13)

OA OB = 9(-3) + 9(1) + 5(13)

= -27 + 9 + 65 = 47

Answer: (3)

JEE Main 2025 (Online) 4th April Morning Shift

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2

Let A be the point of intersection of the lines L1: x-71= y-50= z-3-1 and L2: x-13= y+34= z+75. Let B and C be the points on the lines L1 and L2 respectively such that AB=AC= 15. Then the square of the area of the triangle ABC is :

  1. 63
  2. 57
  3. 60
  4. 54
JEE Main 2025 (Online) 4th April Evening Shift
3

Let the values of p, for which the shortest distance between the lines x+13= y4= z5 and r=(p i+2 j+ k)+ (2 i+3 j+4 k) is 1 6, be a, b, (a<b). Then the length of the latus rectum of the ellipse x2a2+ y2b2=1 is :

  1. 32
  2. 9
  3. 18
  4. 23
JEE Main 2025 (Online) 4th April Evening Shift
4

Let a line passing through the point (4, 1, 0) intersect the line L1 : x-12 = y-23 = z-34 at the point A( , , ) and the line L2 : x - 6 = y = -z + 4 at the point B(a, b, c). Then vmatrix 1 & 0 & 1 \ & & \ a & b & c vmatrix is equal to

  1. 16
  2. 6
  3. 8
  4. 12
JEE Main 2025 (Online) 3rd April Morning Shift
5

Line L1 passes through the point (1, 2, 3) and is parallel to z-axis. Line L2 passes through the point ( , 5, 6) and is parallel to y-axis. Let for = 1, 2, 2 < 1, the shortest distance between the two lines be 3. Then the square of the distance of the point ( 1, 2, 7) from the line L1 is

  1. 25
  2. 32
  3. 40
  4. 37
JEE Main 2025 (Online) 3rd April Morning Shift
6

Each of the angles and that a given line makes with the positive y- and z-axes, respectively, is half of the angle that this line makes with the positive x-axis. Then the sum of all possible values of the angle is

  1. 2
  2. 3 4
  3. 3 2
JEE Main 2025 (Online) 3rd April Evening Shift
7

The distance of the point (7, 10, 11) from the line x-41 = y-40 = z-23 along the line x-92 = y-133 = z-176 is

  1. 16
  2. 12
  3. 18
  4. 14
JEE Main 2025 (Online) 3rd April Evening Shift
8

Let the vertices Q and R of the triangle PQR lie on the line x+35 = y-12 = z+43, QR = 5 and the coordinates of the point P be (0, 2, 3). If the area of the triangle PQR is mn then :

  1. 2m - 5 21 n = 0
  2. m - 5 21 n = 0
  3. 5m - 21 2 n = 0
  4. 5m - 2 21 n = 0
JEE Main 2025 (Online) 2nd April Morning Shift
9

If the image of the point P(1, 0, 3) in the line joining the points A(4, 7, 1) and B(3, 5, 3) is Q( , , ), then + + is equal to :

  1. 463
  2. 18
  3. 13
  4. 473
JEE Main 2025 (Online) 2nd April Evening Shift
10

The line L1 is parallel to the vector a = -3 i + 2 j + 4 k and passes through the point (7, 6, 2) and the line L2 is parallel to the vector b = 2 i + j + 3 k and passes through the point (5, 3, 4). The shortest distance between the lines L1 and L2 is :

  1. 23 38
  2. 21 38
  3. 23 57
  4. 21 57
JEE Main 2025 (Online) 2nd April Evening Shift
11

Let L1 : x-11 = y-2-1 = z-12 and L2 : x+1-1 = y-22 = z1 be two lines. Let L3 be a line passing through the point ( , , ) and be perpendicular to both L1 and L2. If L3 intersects L1, then |5 - 11 - 8 | equals :

  1. 25
  2. 20
  3. 16
  4. 18
JEE Main 2025 (Online) 29th January Morning Shift

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