Pure Mathematics · 3rd secondary · First Term

Algebra - Geometry and measurement in two and three dimensions — Vectors in space

About this lesson

This unit introduces vectors in three-dimensional space (R3). It begins by defining the position vector of a point with respect to the origin, its components along the x, y, and z axes, and the norm (length) of a vector. It then covers vector operations: addition, scalar multiplication, and equality of vectors, along with their algebraic properties. The unit also explains the fundamental unit vectors i, j, k, how to express any vector in terms of these unit vectors, and how to express a directed line segment between two points using their coordinates. Finally, it defines the unit vector in the direction of a given vector, and introduces direction angles and direction cosines, showing how to find them and how to express a vector given its norm and direction angles. The text includes worked examples, 'try to solve' exercises, and a set of mixed exercises at the end.

Main topics in this lesson

  • Vectors in space (three-dimensional coordinate system)
  • Position vector and components
  • Norm of a vector
  • Vector addition and scalar multiplication
  • Equality of vectors
  • Fundamental unit vectors (i, j, k)
  • Expressing vectors in terms of unit vectors
  • Directed line segment between two points
  • Unit vector in the direction of a vector
  • Direction angles and direction cosines

Key terms and vocabulary

  • vector
  • position vector
  • component
  • norm
  • unit vector
  • fundamental unit vectors
  • i, j, k
  • scalar
  • addition
  • scalar multiplication
  • equality of vectors
  • directed line segment
  • direction angles
  • direction cosines
  • R3

Questions and answers on Algebra - Geometry and measurement in two and three dimensions — Vectors in space - practice and revision

Multiple choice questions on this lesson in Pure Mathematics for 3rd secondary, First Term, with practice exercises for revision and exam preparation.

1

إذا كان أ = i + j + k، فإن مجموع مربعات جيوب تمام الاتجاه للمتجه أ يساوي:

  • 1 1
  • 2 3
  • 3 1/3
  • 4 جذر 3
2

إذا كان أ = 6i - 2j + 3k، فإن متجه الوحدة في اتجاه أ هو:

  • 1 (6/7)i - (2/7)j + (3/7)k
  • 2 (6/49)i - (2/49)j + (3/49)k
  • 3 42i - 14j + 21k
  • 4 (1/7)i - (1/7)j + (1/7)k
3

إذا كان أ = 2i + 2j + k، فإن جتا الزاوية التي يصنعها أ مع محور x يساوي:

  • 1 2/3
  • 2 1/3
  • 3 2/9
  • 4 3/2
4

إذا كان أ = 3i + 4j، ب = -i + 2j + k، فإن أ - ب يساوي:

  • 1 4i + 2j - k
  • 2 2i + 6j + k
  • 3 4i + 2j + k
  • 4 2i + 2j - k
5

إذا كان أ = 2i - 2j + k، فإن طول المتجه أ يساوي:

  • 1 3
  • 2 9
  • 3 5
  • 4 1
6

إذا كان أ = i + 2j + 2k، فإن جتا الزاوية التي يصنعها أ مع محور y يساوي:

  • 1 2/3
  • 2 1/3
  • 3 2/9
  • 4 3

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