Math Problem Statement

Find a unit vector that has the same direction as the given vector -3i + 8j.

Solution

This problem requires finding a unit vector that has the same direction as the given vector a=3i+8j\mathbf{a} = -3\mathbf{i} + 8\mathbf{j}.

Steps to solve:

  1. Find the magnitude (length) of the vector a\mathbf{a}: The formula for the magnitude of a vector a=a1i+a2j\mathbf{a} = a_1\mathbf{i} + a_2\mathbf{j} is: a=a12+a22|\mathbf{a}| = \sqrt{a_1^2 + a_2^2} Here, a1=3a_1 = -3 and a2=8a_2 = 8. Substituting these values: a=(3)2+82=9+64=73.|\mathbf{a}| = \sqrt{(-3)^2 + 8^2} = \sqrt{9 + 64} = \sqrt{73}.

  2. Divide the vector by its magnitude to get the unit vector: The formula for a unit vector u\mathbf{u} in the same direction as a\mathbf{a} is: u=aa.\mathbf{u} = \frac{\mathbf{a}}{|\mathbf{a}|}. Substituting a=3i+8j\mathbf{a} = -3\mathbf{i} + 8\mathbf{j} and a=73|\mathbf{a}| = \sqrt{73}: u=3i+8j73=(373)i+(873)j.\mathbf{u} = \frac{-3\mathbf{i} + 8\mathbf{j}}{\sqrt{73}} = \left(\frac{-3}{\sqrt{73}}\right)\mathbf{i} + \left(\frac{8}{\sqrt{73}}\right)\mathbf{j}.

  3. Simplify or approximate values (if needed): The components of u\mathbf{u} are approximately: 3730.351,8730.937.\frac{-3}{\sqrt{73}} \approx -0.351, \quad \frac{8}{\sqrt{73}} \approx 0.937. Therefore: u0.351i+0.937j.\mathbf{u} \approx -0.351\mathbf{i} + 0.937\mathbf{j}.

Let me know if you'd like a deeper explanation or further assistance with any part of the solution!


Here are 5 related questions for practice:

  1. How do you verify if a given vector is a unit vector?
  2. What happens to the direction of a vector when converted to a unit vector?
  3. How would you find a unit vector in three-dimensional space?
  4. What is the unit vector of a=6i2j\mathbf{a} = 6\mathbf{i} - 2\mathbf{j}?
  5. How do you interpret unit vectors in physics or engineering applications?

Tip:

Always double-check your magnitude calculations to ensure accuracy when normalizing vectors.

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Math Problem Analysis

Mathematical Concepts

Vector Operations
Unit Vectors
Magnitude of a Vector

Formulas

Magnitude of a vector |a| = sqrt(a1^2 + a2^2)
Unit vector u = a / |a|

Theorems

Definition of Unit Vector

Suitable Grade Level

Grades 10-12