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Finding the Unit Vector of a Vector

Every nonzero vector has a corresponding unit vector, which has the same direction as that vector but a magnitude of 1. To find the unit vector u of the vector

image0.png

you divide that vector by its magnitude as follows:

image1.png

Note that this formula uses scalar multiplication, because the numerator is a vector and the denominator is a scalar.

A scalar is just a fancy word for a real number. The name arises because a scalar scales a vector — that is, it changes the scale of a vector. For example, the real number 2 scales the vector v by a factor of 2 so that 2v is twice as long as v.

As you may guess from its name, the unit vector is a vector.

For example, to find the unit vector u of the vector

image2.png

you first calculate its magnitude |q|:

image3.png

Now use the previous formula to calculate the unit vector:

image4.png

You can check that the magnitude of resulting vector u really is 1 as follows:

image5.png
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