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Three Dimensional Geometry

JEE Main 2025 (Online) 29th January Morning ShiftMCQEasy📈 Topic in 36% papers+4−1
Ques. 1JEE Main 2025, 29 January (Morning Shift)

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)

Answer

(3) (8, 26, 12)

Solution

A general point of L1 is (-1 + , 2 + 2 , 1 + ) and of L2 is (2 , 1 + 7 , 1 + 3 ).

At the point of intersection,

1 + = 1 + 3 = 3

-1 + = 2 -1 + 3 = 2 = 1, = 3

Check y : 2 + 2(3) = 8 = 1 + 7(1) ✓

so the point of intersection is (2, 8, 4).

With a + b = 3 i + 9 j + 4 k as direction,

L3 : x - 23 = y - 89 = z - 44 = t

and its general point is (2 + 3t, 8 + 9t, 4 + 4t).

For t = 2 this is (8, 26, 12), which lies on L3.

(For the other options no single value of t satisfies all three coordinates.)

Answer: (3)

Keep practising — Three Dimensional Geometry

Ques. 2JEE Main 2025, 29 January (Evening Shift)

Let a straight line L pass through the point P(2, -1, 3) and be perpendicular to the lines x-12 = y+11 = z-3-2 and x-31 = y-23 = z+24. If the line L intersects the yz-plane at the point Q, then the distance between the points P and Q is:

  1. 10
  2. 2
  3. 2 3
  4. 3
Ques. 3JEE Main 2025, 29 January (Evening Shift)

Let P be the foot of the perpendicular from the point (1,2,2) on the line L: x-11= y+1-1= z-22. Let the line r= (- i+ j-2 k )+ ( i- j+ k ), , intersect the line L at Q. Then 2(PQ)2 is equal to :

  1. 25
  2. 27
  3. 19
  4. 29
Ques. 4JEE Main 2025, 28 January (Morning Shift)

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
Ques. 5JEE Main 2025, 28 January (Evening Shift)

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
Ques. 6JEE Main 2025, 24 January (Morning Shift)

Let in a ABC, the length of the side AC be 6, the vertex B be (1,2,3) and the vertices A, C lie on the line x-63= y-72= z-7-2. Then the area (in sq. units) of ABC is:

  1. 42
  2. 17
  3. 56
  4. 21
Ques. 7JEE Main 2025, 24 January (Morning Shift)

Let the line passing through the point (-1,2,1) and parallel to the line x-12= y+13= z4 intersect the line x+23= y-32= z-41 at the point P. Then the distance of P from the point Q(4,-5,1) is

  1. 5 6
  2. 5
  3. 5 5
  4. 10
Ques. 8JEE Main 2025, 24 January (Evening Shift)

Let P be the image of the point Q(7,-2,5) in the line L: x-12= y+13= z4 and R(5,p,q) be a point on L. Then the square of the area of PQR is .

Ques. 9JEE Main 2025, 23 January (Morning Shift)

Let P be the foot of the perpendicular from the point Q(10,-3,-1) on the line x-37= y-2-1= z+1-2. Then the area of the right angled triangle PQR, where R is the point (3,-2,1), is

  1. 30
  2. 9 15
  3. 3 30
  4. 8 15
Ques. 10JEE Main 2025, 23 January (Evening Shift)

If the square of the shortest distance between the lines x-21= y-12= z+3-3 and x+12= y+34= z+5-5 is mn, where m, n are coprime numbers, then m+n is equal to :

  1. 14
  2. 6
  3. 21
  4. 9
Ques. 11JEE Main 2025, 23 January (Evening Shift)

The distance of the line x-22= y-63= z-34 from the point (1,4,0) along the line x1= y-22= z+33 is :

  1. 17
  2. 13
  3. 15
  4. 14

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