+226 Let u,v and w be vectors satisfying u∙v=3,u∙w=4,v∙w=5.
Then what are (u+2v)∙w,(w−u)∙v,(3v−2w)∙u equal to?
+226 It would be
3(v•u) - 2(w•u) = -3(u•v) + 2(u•w) = -3x3 + 2x4 = -9 + 8 = -1
right?
+33654 Apologies, I've misled you by reacting too quickly, with too little thought!
With dot products u•v = |u|*|v|*cos(theta), where |u| is the magnitude of u, and theta is the angle between u and v. This means that
v•u = |v|*|u|*cos(theta) = u•v
The same is true for the other dot products.
+226 So that would mean
the second one is 5-3 =2
the third is 9-8 = 1
right?
