Mathematics
Grade 12
15 min
Add and subtract threedimensional vectors
Add and subtract threedimensional vectors
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1
Introduction & Learning Objectives
Learning Objectives
Represent three-dimensional vectors in component form and unit vector form.
Add two or more three-dimensional vectors algebraically by summing their corresponding components.
Subtract one three-dimensional vector from another by subtracting their corresponding components.
Interpret the results of vector addition and subtraction geometrically using the head-to-tail rule and the parallelogram rule.
Solve for a resultant vector in problems that combine scalar multiplication with vector addition and subtraction.
Calculate the vector between two points in 3D space using vector subtraction.
How does an air traffic controller predict a plane's final position when it's being pushed by wind? ✈️ They use three-dimensional vector addition to find the true...
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Key Concepts & Vocabulary
TermDefinitionExample
Three-Dimensional VectorA mathematical object that has both magnitude (length) and direction, existing in a three-dimensional (x, y, z) coordinate system.The vector v = <3, 4, 5> represents a displacement of 3 units along the x-axis, 4 units along the y-axis, and 5 units along the z-axis.
Component FormA way of writing a vector by listing its components along the x, y, and z axes, enclosed in angle brackets.If a vector starts at the origin and ends at the point (2, -1, 4), its component form is v = <2, -1, 4>.
Standard Unit VectorsVectors of length 1 that point along the positive x, y, and z axes. They are denoted by i, j, and k, respectively.i = <1, 0, 0>, j = <0, 1, 0>, k = <0, 0, 1>. The vector <2, -1, 4> can be written as 2i -...
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Core Formulas
Vector Addition Formula
Let u = <u_x, u_y, u_z> and v = <v_x, v_y, v_z>. Then u + v = <u_x + v_x, u_y + v_y, u_z + v_z>.
To add two three-dimensional vectors, add their corresponding components. Add the x-components together, the y-components together, and the z-components together.
Vector Subtraction Formula
Let u = <u_x, u_y, u_z> and v = <v_x, v_y, v_z>. Then u - v = <u_x - v_x, u_y - v_y, u_z - v_z>.
To subtract one vector from another, subtract their corresponding components. Subtract the second vector's components from the first vector's components for each axis.
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Challenging
Let w = u + v and z = u - v. If u = <2, 0, 5> and v = <3, -1, -1>, find the vector 2w - z.
A.<7, -1, 14>
B.<11, -3, 2>
C.<9, -1, 10>
D.<1, 1, 6>
Challenging
Points P and Q have position vectors p = <2, 6, -1> and q = <8, -2, 11> respectively, relative to the origin O. If M is the midpoint of the line segment PQ, what is the vector OM?
A.<6, -8, 12>
B.<3, -4, 6>
C.<10, 4, 10>
D.<5, 2, 5>
Challenging
Solve the following system of vector equations for vector x: x + y = <8, 1, 7> and x - y = <2, 5, -3>
A.<10, 6, 4>
B.<6, -4, 10>
C.<5, 3, 2>
D.<3, -2, 5>
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