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Three Dimensional Geometry · Question 41

JEE Main 2025 (Online) 4th April Evening ShiftMCQMedium📈 Topic in 10% papers+4−1
1

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

Answer

(4) 54

Solution

Any point of L1: (7+t, 5, 3-t); any point of L2: (1+3s, -3+4s, -7+5s)

At the point of intersection: 5=-3+4s s=2

7+t=1+6 t=0; check z: 3-0=-7+10=3

A=(7, 5, 3)

Directions: b1= i- k, b2=3 i+4 j+5 k

= |3+0-5| 2 50= 210= 15

= 1- 125= 245

B lies on L1 and C on L2, BAC= or - ; in both cases BAC= 245

Area = 12 AB AC BAC= 12 15 245= 3 242

(Area)2= 9 244=54

Answer: (4)

JEE Main 2025 (Online) 4th April Evening Shift

Keep practising — Three Dimensional Geometry

2

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
3

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
4

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
5

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
6

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
7

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
8

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
9

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
10

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
11

Let a = i + 2 j + k and b = 2 i + 7 j + 3 k. Let L1 : r = (- i + 2 j + k) + a, R and L2 : r = ( j + k) + b, R be two lines. If the line L3 passes through the point of intersection of L1 and L2 and is parallel to a + b, then L3 passes through the point :

  1. (-1, -1, 1)
  2. (2, 8, 5)
  3. (8, 26, 12)
  4. (5, 17, 4)
JEE Main 2025 (Online) 29th January Morning Shift

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