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Three Dimensional Geometry · Question 47

JEE Main 2025 (Online) 2nd April Morning ShiftMCQEasy📈 Topic in 68% papers+4−1
1

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

Answer

(1) 2m - 5 21 n = 0

Solution

The line passes through A(-3, 1, -4) with direction b = 5 i + 2 j + 3 k.

AP = 3 i + j + 7 k

AP b = vmatrix i & j & k \ 3 & 1 & 7 \ 5 & 2 & 3 vmatrix = -11 i + 26 j + k

Distance of P from the line (height of the triangle):

h = | AP b|| b| = 121 + 676 + 1 38 = 79838 = 21

Area of PQR = 12 QR h = 12 5 21 = 5 212

mn = 5 212 2m = 5 21 n

2m - 5 21 n = 0

Answer: (1)

JEE Main 2025 (Online) 2nd April Morning Shift

Keep practising — Three Dimensional Geometry

2

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
3

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
4

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
5

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
6

If the image of the point (4, 4, 3) in the line x - 12 = y - 21 = z - 13 is ( , , ), then + + is equal to

  1. 12
  2. 9
  3. 7
  4. 8
JEE Main 2025 (Online) 28th January Morning Shift
7

The square of the distance of the point ( 157, 327, 7 ) from the line x+13 = y+35 = z+57 in the direction of the vector i + 4 j + 7 k is:

  1. 66
  2. 54
  3. 41
  4. 44
JEE Main 2025 (Online) 28th January Evening Shift

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