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### Course: Precalculus>Unit 6

Lesson 1: Vectors introduction

# Representing quantities with vectors

Vectors can represent real-world quantities where it's important to have both a magnitude and a direction. One example for that is force: you want to represent a force's magnitude (or strength), but it's also important to indicate in what direction the force is applied. Created by Sal Khan.

## Want to join the conversation?

• Does 20 degrees mean clockwise from the east direction of the ball? Not 20 degrees in the first quadrant, which is counter-clockwise?
• You're correct! In this situation, it is 20° clockwise from the eastward direction because they said, "20° to the south from the eastward direction relative to the ball." If you rotate 20° southward from the eastward direction, it is like rotating clockwise. Note that if it was just 20° on a standard coordinate plane, if would be 20° counter-clockwise.
``                      N                      |                 W —— + —— E                      |                        S``