Calculating the Main Diagonal of a Parallelepiped from Origin to Opposite Vertex

[Minihoudini]

The question is:
let V1=(2,2,0), V2=(-1,2,1), V3-(1,1,4). There three vectors determine a parallelepiped. P draw it.
(a) (this is the one that is giving me trouble) Determine the length of its main diagonal. (from origin to opposite vertex).

I can't seem to figure out what it means from the origin to the opposite vertex. I've drawn the graph and originally I thought I would have to take the determine of two vectors then find the length of it. I'm just pretty lost here. Once I get this part and I know what its asking of me I can get the other problems easily.

 

[mathman]

The origin is (0,0,0). The opposite vertex is the point at the end of the vector V1+V2+v3 (with one end at the origin), that is (2,5,5).

I assume you know how to get this length.

 

[Minihoudini]

thanks, that helped a lot