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Three Dimensional Geometry · Question 36

JEE Main 2025 (Online) 7th April Morning ShiftMCQMedium📈 Topic in 35% papers+4−1
1

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

Answer

(3) -3

Solution

Line 1: a1 = (1, 2, 3), b1 = (2, 3, 4); Line 2: a2 = (0, 0, 5), b2 = (1, , 1)

a2 - a1 = (-1, -2, 2)

b1 b2 = vmatrix i & j & k \ 2 & 3 & 4 \ 1 & & 1 vmatrix = (3 - 4 , 2, 2 - 3)

| b1 b2|2 = (3-4 )2 + 4 + (2 -3)2 = 20 2 - 36 + 22

( a2 - a1) ( b1 b2) = -(3-4 ) - 4 + 2(2 -3) = 8 - 13

|8 - 13| 20 2 - 36 + 22 = 5 6

6(64 2 - 208 + 169) = 25(20 2 - 36 + 22)

116 2 + 348 - 464 = 0

2 + 3 - 4 = 0 = 1, -4

(Both are valid; the lines are never parallel since 12 14.)

sum of all possible values of = 1 + (-4) = -3

Answer: (3)

JEE Main 2025 (Online) 7th April Morning Shift

Keep practising — Three Dimensional Geometry

2

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
3

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
4

Let the shortest distance between the lines x-33 = y- -1 = z-31 and x+3-3 = y+72 = z- 4 be 3 30. Then the positive value of 5 + is

  1. 42
  2. 40
  3. 48
  4. 46
JEE Main 2025 (Online) 4th April Morning Shift
5

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
JEE Main 2025 (Online) 4th April Morning Shift
6

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
7

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
8

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
9

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
10

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
11

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
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