Direction of a vector relative to another vector?

Hello, I have two vectors, the angle between them is dynamic and constantly changing. I have found a way to calculate the angle between these two vectors. But this angle is always a positive number even if i am looking left or right. How can i get context(wether vector DC,DB,DE,DF according to the image below) is to the right of vector DA or to the left of it?

http://oi42.tinypic.com/2prwfo0.jpg

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