Math Problem Statement

Calculate the vector cross product of [8, 8, 6] and [5, 6, 4].

Solution

To calculate the cross product of the vectors given:

A=[886]andB=[564],\mathbf{A} = \begin{bmatrix} 8 \\ 8 \\ 6 \end{bmatrix} \quad \text{and} \quad \mathbf{B} = \begin{bmatrix} 5 \\ 6 \\ 4 \end{bmatrix},

we can use the formula for the cross product of two vectors in R3\mathbb{R}^3, represented as:

A×B=ijk886564\mathbf{A} \times \mathbf{B} = \begin{vmatrix} \mathbf{i} & \mathbf{j} & \mathbf{k} \\ 8 & 8 & 6 \\ 5 & 6 & 4 \end{vmatrix}

Expanding the determinant, we get:

A×B=i8664j8654+k8856\mathbf{A} \times \mathbf{B} = \mathbf{i} \cdot \begin{vmatrix} 8 & 6 \\ 6 & 4 \end{vmatrix} - \mathbf{j} \cdot \begin{vmatrix} 8 & 6 \\ 5 & 4 \end{vmatrix} + \mathbf{k} \cdot \begin{vmatrix} 8 & 8 \\ 5 & 6 \end{vmatrix}

Calculating each minor:

  1. For i\mathbf{i}: 8664=(84)(66)=3236=4\begin{vmatrix} 8 & 6 \\ 6 & 4 \end{vmatrix} = (8 \cdot 4) - (6 \cdot 6) = 32 - 36 = -4

  2. For j\mathbf{j}: 8654=(84)(65)=3230=2\begin{vmatrix} 8 & 6 \\ 5 & 4 \end{vmatrix} = (8 \cdot 4) - (6 \cdot 5) = 32 - 30 = 2

  3. For k\mathbf{k}: 8856=(86)(85)=4840=8\begin{vmatrix} 8 & 8 \\ 5 & 6 \end{vmatrix} = (8 \cdot 6) - (8 \cdot 5) = 48 - 40 = 8

Putting it all together:

A×B=4i2j+8k\mathbf{A} \times \mathbf{B} = -4 \mathbf{i} - 2 \mathbf{j} + 8 \mathbf{k}

So, the cross product is:

A×B=[428]\mathbf{A} \times \mathbf{B} = \begin{bmatrix} -4 \\ -2 \\ 8 \end{bmatrix}

Let me know if you need any more details!


Questions for Further Exploration:

  1. What is the geometric interpretation of a cross product?
  2. How does the cross product differ from the dot product in terms of properties?
  3. Can cross products be used for vectors in higher dimensions?
  4. Why does the cross product only apply to 3-dimensional vectors?
  5. How does the direction of the resulting vector relate to the original vectors?

Tip:

Remember that the cross product of two vectors results in a vector that is perpendicular to both original vectors, which follows the right-hand rule.

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Math Problem Analysis

Mathematical Concepts

Vector Calculus
Cross Product

Formulas

Cross Product Formula for Vectors in R^3: A x B = |i j k| |a1 a2 a3| |b1 b2 b3|

Theorems

Properties of Cross Product
Right-Hand Rule

Suitable Grade Level

Undergraduate