What is the dot product of r = (6, 0)T with s = (0, 8)T?
(6, 0)T · (0, 8)T = 6*0 + 0*8 = 0
The question was a particularly easy case. Here are the same two vectors rotated 45o:
Don't worry too much about how I got the rotatated vectors. This topic will come up soon enough.
Form the dot product of the two vectors:
(Yes, I know, this looks an awful lot like trigonometry. But it isn't. Just do it.)