Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NDA2024MathematicsThree Dimensional GeometryActual

If a vector of magnitude 2 units makes an angle 3 with 2 i , 4 with 3 j and an acute angle with 4 k , then what are the components of the vector?

Options

  1. A(1, 2 , 1)
  2. B(1,- 2 , 1)
  3. C(1,- 2 ,-1)
  4. D(1, 2 ,-1)

Correct answer

A. (1, 2 , 1)

Step-by-step solution

Let, a have (a₁, a₂, a₃ ) components array ll & a₁ i +a₂ j +a₃ k & | a |=2 array Also, It is given that a make angle with 3 with 2 i , 4 with 3 j and an acute angle with 4 k Then we have, aligned a 2 i & =| a ||2 i | 3 (a₁ i +a₂ j +a₃ k ) 2 i & =2.2 1 2 2 a₁ & =2 a₁=1 a 3 j & =| a ||3 j | 4 aligned and 3 a₂=2 3 1 2 a₂= 2 aligned a 4 k & =| a ||4 k | 4 a₃ & =2 4 aligned = a₃ 2 Now, | a |=2 array ll & a₁^2+a₂^2+a₃^2 =2 & a₁^2+a₂^2+a₃^2=4 array Put, a₁=1 and a₂= 2 (1)^2+( 2 )^2+a₃^2=4 a₃^2= 1 When, a₃=-1 then, =- 1 2

Practice Three Dimensional Geometry on Quantrex Academy →

More from Three Dimensional Geometry

Passage: The equation of the sphere S is x^2+y^2+z^2-4x-6y-12z+k=0 . Question: If the radius of the sphere S is 8 units, what is the value of k ? 2026Passage: A line L passing through the point (-1,2,-3) is perpendicular to the plane P given by 2x+3y+z+5=0 . Question: What is the equation of the line L ? 2026Passage: P(-2,-3,5) , Q(4,-1,5) , R(6,-4,8) and S(2,-6,10) are four points. Question: Consider the following statements : I. PQ is parallel to RS . II. PR is perpendicular to QS . 2026Passage: A line L passing through the point (-1,2,-3) is perpendicular to the plane P given by 2x+3y+z+5=0 . Question: What are the direction ratios of a line M parallel to the pla 2026Passage: P(-2,-3,5) , Q(4,-1,5) , R(6,-4,8) and S(2,-6,10) are four points. Question: What is (PQ^2+2QS^2-2PR^2) equal to ? 2026Passage: The equation of the sphere S is x^2+y^2+z^2-4x-6y-12z+k=0 . Question: What is the radius of the sphere passing through origin and concentric with the sphere S ? 2026For the following two (02) items: A plane P is parallel to the line having direction ratios 1, 3, 2 and contains the line of intersection of the planes 6x + 4y - 5z = 2 and x - 2y 2025For the following two (02) items: Suppose S is the sphere with the smallest radius that passes through the points A(1, 0, 0) , B(0, 1, 0) and C(0, 0, 1) . On which one of the follo 2025 Full Three Dimensional Geometry list All NDA PYQs