Problem 13 - Precalculus Mathematics for Calculus

Question

Find the magnitude of the given vector. $$(3,5,-4)$$

Step-by-Step Solution

Answer

\(5\sqrt{2} \approx 7.07\)

Step 1: Apply the Magnitude Formula

\(\|\mathbf{v}\| = \sqrt{3^2 + 5^2 + (-4)^2} = \sqrt{9 + 25 + 16} = \sqrt{50} = 5\sqrt{2}\)

Step 2: Approximate

\(5\sqrt{2} \approx 7.07\)

Key Concepts

vectors

Vectors are mathematical objects used to represent quantities that have both magnitude and direction.
Vectors are often visually depicted as arrows pointing in a certain direction, where the length of the arrow indicates the magnitude of the vector. In mathematics and physics, vectors are used to describe velocities, forces, and other directional quantities.

• Components: A vector in space can be broken down into its components, typically represented as coordinates. For example, a vector can be written as \((x, y)\) in two-dimensional space or \((x, y, z)\) in three-dimensional space.
• Notation: Vectors are notated with boldface type or with an arrow above the letter, such as \( \vec{v} \) or v.
• Operations: Vectors can be added together, subtracted from one another, and multiplied by a scalar. Each of these operations has specific rules that respect the directional nature of vectors.

Understanding vectors is vital for solving problems in fields such as physics, engineering, and computer science, where it's important to account for direction as well as magnitude.

magnitude formula

The magnitude of a vector is a measure of its length. It tells you how "long" a vector is without regard to its direction. To compute the magnitude of a vector, we use a specific formula.

Magnitude Formula for Three-Dimensional Vectors

If you have a vector \( \vec{v} = (x, y, z) \), its magnitude \( |\vec{v}| \) is calculated by the formula:\[|\vec{v}| = \sqrt{x^2 + y^2 + z^2}\]
This formula is derived from extending the Pythagorean theorem to three dimensions, where \( x, y, \) and \( z \) are the respective components of the vector.

• The squared values \( x^2, y^2, \) and \( z^2 \) ensure each component's contribution to the vector's magnitude is considered.
• The square root ensures the result is in the original units of the vector components, representing a distance.

Using the magnitude formula allows you to quantify the "size" of a vector, which is especially useful in analyzing physical systems and performing vector-related calculations.

three-dimensional vectors

Three-dimensional vectors extend the concept of vectors into space that includes length, width, and height. These vectors are crucial for modeling and understanding real-world situations where more complex spatial orientations are involved.

Defining Three-Dimensional Vectors

A three-dimensional vector \( \vec{v} \) can be expressed as \( (x, y, z) \), where:

• \( x \): is the component along the x-axis (horizontal direction).
• \( y \): is the component along the y-axis (vertical direction).
• \( z \): is the component along the z-axis (depth direction).

Applications of Three-Dimensional Vectors

Three-dimensional vectors are widely used in various applications, including:

• Physics: Describing forces, velocities, and other vector quantities in scenarios involving depth.
• Computer Graphics: Modeling scenes and transformations in 3D space.
• Engineering: Design and analysis of structures and systems in three-dimensional space.

Three-dimensional vectors provide a robust framework for complex spatial analysis and problem-solving, enabling a deeper exploration of multi-dimensional systems.