Math Problem Statement

find the component form of the unit vector that makes the angle -3pi/4 with a positive x axis

Solution

To find the component form of a unit vector that makes an angle 3π4-\frac{3\pi}{4} with the positive xx-axis, we can use the following general formula for the unit vector in two dimensions:

v=cos(θ),sin(θ)\mathbf{v} = \langle \cos(\theta), \sin(\theta) \rangle

Where:

  • θ\theta is the angle with the positive xx-axis.
  • Since we want a unit vector, the magnitude will always be 1.

Given that θ=3π4\theta = -\frac{3\pi}{4}, we plug it into the formula:

v=cos(3π4),sin(3π4)\mathbf{v} = \langle \cos\left(-\frac{3\pi}{4}\right), \sin\left(-\frac{3\pi}{4}\right) \rangle

Step 1: Compute the trigonometric values

  • cos(3π4)=12\cos\left(-\frac{3\pi}{4}\right) = -\frac{1}{\sqrt{2}}
  • sin(3π4)=12\sin\left(-\frac{3\pi}{4}\right) = \frac{1}{\sqrt{2}}

Step 2: Write the component form of the vector

Thus, the unit vector in component form is:

v=12,12\mathbf{v} = \langle -\frac{1}{\sqrt{2}}, \frac{1}{\sqrt{2}} \rangle

Alternatively, you could express it as:

v=22,22\mathbf{v} = \langle -\frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2} \rangle

This is the component form of the unit vector.

Would you like further details or have any other questions?


Here are 5 related questions:

  1. How do you convert angles from radians to degrees?
  2. What is the general formula for finding the magnitude of any vector?
  3. How do you find the direction of a vector if given in component form?
  4. Can you explain how unit vectors are used in physics?
  5. What is the significance of the negative angle in this problem?

Tip: Always remember that a unit vector has a magnitude of 1, which simplifies many vector calculations!

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Unit Vectors
Radians

Formulas

Unit vector formula: v = ⟨cos(θ), sin(θ)⟩

Theorems

Trigonometric functions for standard angles

Suitable Grade Level

Grades 10-12