Math Problem Statement

Let
→ a

⟨ 0 , 2 , − 3 ⟩ and
→ b

⟨ 1 , − 3 , 5 ⟩ .

Find the angle between the vector (in radians)

Solution

The angle θ\theta between two vectors a\mathbf{a} and b\mathbf{b} can be found using the dot product formula:

cos(θ)=abab\cos(\theta) = \frac{\mathbf{a} \cdot \mathbf{b}}{|\mathbf{a}| |\mathbf{b}|}

Step 1: Find the dot product ab\mathbf{a} \cdot \mathbf{b}

Given: a=0,2,3andb=1,3,5\mathbf{a} = \langle 0, 2, -3 \rangle \quad \text{and} \quad \mathbf{b} = \langle 1, -3, 5 \rangle

The dot product is calculated as:

ab=(0)(1)+(2)(3)+(3)(5)=0615=21\mathbf{a} \cdot \mathbf{b} = (0)(1) + (2)(-3) + (-3)(5) = 0 - 6 - 15 = -21

Step 2: Find the magnitudes a|\mathbf{a}| and b|\mathbf{b}|

a=02+22+(3)2=0+4+9=13|\mathbf{a}| = \sqrt{0^2 + 2^2 + (-3)^2} = \sqrt{0 + 4 + 9} = \sqrt{13}

b=12+(3)2+52=1+9+25=35|\mathbf{b}| = \sqrt{1^2 + (-3)^2 + 5^2} = \sqrt{1 + 9 + 25} = \sqrt{35}

Step 3: Use the formula to find θ\theta

cos(θ)=211335=21455\cos(\theta) = \frac{-21}{\sqrt{13} \cdot \sqrt{35}} = \frac{-21}{\sqrt{455}}

θ=cos1(21455)\theta = \cos^{-1}\left( \frac{-21}{\sqrt{455}} \right)

Let me calculate the exact value of the angle.The angle between the vectors a=0,2,3\mathbf{a} = \langle 0, 2, -3 \rangle and b=1,3,5\mathbf{b} = \langle 1, -3, 5 \rangle is approximately 2.965 radians.

Would you like more details or have any further questions?

Here are some related questions:

  1. How do you calculate the dot product between two vectors?
  2. What is the physical interpretation of the angle between two vectors?
  3. How would you calculate the angle between two vectors in degrees instead of radians?
  4. What does it mean when the dot product of two vectors is zero?
  5. How can the magnitude of a vector be interpreted geometrically?

Tip: The dot product can be useful in determining if two vectors are orthogonal, parallel, or have some general angle between them.

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Math Problem Analysis

Mathematical Concepts

Vector Algebra
Dot Product
Trigonometry

Formulas

Dot Product: a · b = a₁b₁ + a₂b₂ + a₃b₃
Magnitude of a Vector: |a| = √(a₁² + a₂² + a₃²)
Cosine of the Angle Between Two Vectors: cos(θ) = (a · b) / (|a| * |b|)

Theorems

Cosine Rule for Vectors

Suitable Grade Level

Grades 10-12