# How do you find the angle between the vectors #u=5i+5j# and #v=-6i+6j#?

##### 1 Answer

Nov 2, 2016

Please see the explanation to understand why we know that the angle between the two vectors is

#### Explanation:

Given two vectors of the form:

and

The dot-product is:

Therefore, the dot-product of the two vectors:

Normally, we would use the above dot-product the for the left side of the equation:

And then compute the magnitudes and, ultimately, solve for

But, because the dot-product is zero and we know that the magnitudes cannot be zero, then we know that:

Which means that: