Vectors for calculus 3?

Find u (dot) v, if ll u ll = 40, ll v ll = 15, and the angle between vectors u and v is (2Pi/3).





a) -300 * sqr(3)


b) 900/Pi


c) 300


d) -300


e) none of the above





please be detailstic with your work so that I know what steps you used to work out the problem. thank you

Vectors for calculus 3?
Well, this is just applying the definition of the dot product:


A dot B= ll A ll ll Bllcos(theta), that is a dot b equals the magnitude of A times the magnitude of B times the cosine of the angle between A and B


So, in your case, that would be


(40*15)*cos(2pi/3)=-300
Reply:Try the Orange County California Vector Control Office.
Reply:u.v= ||u|| ||v|| cos (2Pi/3)


=40*15*cos(2pi/3)= 600*(-0.5)=-300


Answer is d