Demonstration colinearity

If two vectors are colinear, their sum will be colinear to each of them.[br]Modify the vector angle [math]\vec{u}[/math] and [math]\vec{v}[/math] cursor measurements and see the angle measurement of their sum. What is this measure if the vectors [math]\vec{u}[/math] and [math]\vec{v}[/math] have the same angle?

Information: Demonstration colinearity