Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
COMEDK202510 May 2025Morning ShiftMathematicsThree Dimensional GeometryActual

The value of for which the angle between lines r = + + k +p(2 + +2 k ) and r =(1+q) +(1+q ) +(1+q) k is 2

Options

  1. A4
  2. B-2
  3. C2
  4. D-4

Correct answer

D. -4

Step-by-step solution

The direction vector of the first line is v ₁ = 2 i + j + 2 k . The second line is given by r = ( i + j + k ) + q( i + j + k ) . Thus, the direction vector of the second line is v ₂ = i + j + k . Since the angle between the lines is 2 , the lines are perpendicular, which implies that the dot product of their direction vectors must be zero. v ₁ v ₂ = 0 (2 i + j + 2 k ) ( i + j + k ) = 0 (2)(1) + (1)( ) + (2)(1) = 0 2 + + 2 = 0 + 4 = 0 = -4 Answer: -4

Practice Three Dimensional Geometry on Quantrex Academy →

More from Three Dimensional Geometry

The circum radius of the triangle formed by the points (2,-1,1),(1,-3,-5) and (3,-4,-4) is 2025Let A (2,3,5), B (-1,3,2), C ( , 5, ) be the vertices of ABC . If the median through the vertex A is equally inclined to the coordinate axes, then 2025Equation of the plane passing through the origin and perpendicular to the planes x+2 y-z=1 and 3 x-4 y+z=5 is 2025If the line joining the points i +2 j and j -2 k intersects the plane passing through the points 2 i - j , 2 j +3 k and k -2 i at r , then r ( i + j + k )= 2025The vector equation of a plane passing through the line of intersection of the planes r ( i -2 k )=3, r (2 j + k )=5 and the point i +2 j +3 k is 2025The points A (-1,2,3), B (2,-3,1), C (3,1,-2) 2025The direction cosines of the line making angles 4 , 3 and (0 < < 2 ) respectively with X , Y and Z axes are 2025If the equation of the plane passing through the point (3,2,5) and perpendicular to the planes 2 x-3 y+5 z=7 and 5 x+2 y-3 z=11 is x+b y+c z+d=0 , then 2 b+3 c+d= 2025 Full Three Dimensional Geometry list All COMEDK PYQs