Why does rotation about an arbitrary axis have degree of freedom 6 I have been trying to figure out why does rotation about an arbitrary axis have degree of freedom 6. I know that it takes two points, each take 3 values to determine in a 3-D space. But what about the rotation angle? Wouldn't that make the degree of freedom increase by 1 to get 7?
The length of the axis is irrelevant and so you can remove one degree of freedom.