Magnitude And Direction Of Vectors - Varsity Tutors

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Magnitude and Direction of Vectors

Study Guide

Key Definition

The magnitude of a vector $\overrightarrow{PQ}$ is the distance between points $P$ and $Q$. It is calculated using $|\overrightarrow{PQ}| = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$. The direction is the angle $\theta$ with the horizontal: first compute $\tan(\theta) = \frac{y_2 - y_1}{x_2 - x_1}$, then $\theta = \arctan\bigl(\frac{y_2 - y_1}{x_2 - x_1}\bigr)$, adjusting for the correct quadrant (e.g., using $\mathrm{atan2}$).

Important Notes

  • Use the Distance Formula to find vector magnitude: $\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$
  • Direction of a vector is measured in degrees or radians (default degrees; specify units clearly)
  • The angle $\theta$ is calculated using $\theta = \arctan\bigl(\frac{y_2 - y_1}{x_2 - x_1}\bigr)$, adjusted for the correct quadrant (e.g., via atan2)
  • Vectors can be represented graphically as arrows
  • Magnitude is always a positive number

Mathematical Notation

$\overrightarrow{PQ}$ represents a vector from $P$ to $Q$$|\overrightarrow{PQ}|$ denotes the magnitude of vector $\overrightarrow{PQ}$$\tan(\theta)$ is the tangent of angle $\theta$$\sqrt{}$ denotes the square root$\theta$ is the angle the vector makes with the horizontal axisRemember to use proper notation when solving problems

Why It Works

Vectors have both magnitude and direction, which are essential for representing quantities in physics and engineering. The mathematical formulas help quantify these properties.

Remember

The magnitude of a vector is found using distance calculations, and direction is found through trigonometric functions like $\tan(\theta)$.

Quick Reference

Magnitude of Vector:$|\overrightarrow{PQ}| = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$Direction of Vector:$\theta = \arctan\bigl(\frac{y_2 - y_1}{x_2 - x_1}\bigr)$ (adjust for quadrant; use atan2)

Understanding Magnitude and Direction of Vectors

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Beginner Explanation

A vector has a starting point and an endpoint. The magnitude is the distance between these two points, calculated using $\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$.Now showing Beginner level explanation.

Practice Problems

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1

Quick Quiz

Single Choice QuizBeginner

What is the magnitude of a vector $\overrightarrow{PQ}$ with initial point $P(1, 1)$ and endpoint $Q(5, 3)$?

A$4.5$B$5$C$3.5$D$6$Check AnswerPlease select an answer for all 1 questions before checking your answers. 1 question remaining.2

Real-World Problem

Question ExerciseIntermediate

Teenager Scenario

A drone flies from point $A(2, 3)$ to point $B(5, 8)$. Calculate the direction of the flight path.Show AnswerClick to reveal the detailed solution for this question exercise.3

Thinking Challenge

Thinking ExerciseIntermediate

Think About This

A boat sails in a direction forming an angle of $\theta$ with the shoreline. If $\tan(\theta) = \frac{3}{4}$, what is the angle $\theta$?

Show AnswerClick to reveal the detailed explanation for this thinking exercise.4

Challenge Quiz

Single Choice QuizAdvanced

Find the magnitude of vector $\overrightarrow{RS}$ where $R(-2, -3)$ and $S(4, 1)$.

A$7.21$B$8$C$6.5$D$5.9$Check AnswerPlease select an answer for all 1 questions before checking your answers. 1 question remaining.

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