# Vectors: Magnitude & Direction (I)

- Author:
- Tim Brzezinski

A vector is a mathematical quantity with both magnitude and direction.
The

**magnitude of vector u**, denoted |**u**|, is it's length. One way to express its direction is to give the angle it makes with a horizontal ray (that points to the right) that is parallel to the positive x-axis. This is called the vector's**direction angle.****See below. You can also change the locations of the vector's initial point and terminal point.****KEY QUESTION:**Given a vector's magnitude and direction, how can you rewrite this vector in component form? < , > ?