Homework SourseUsing vector addition and Law of cosines prove that v u v
Using vector addition and Law of cosines, prove that v ??u ?= ||v ?|| ||u ?|| Cos ?
Solution
= - the angle between the two vectors
v= |v|cos,|v|sin
u=|u|cos,|u|sin
u*v=|u||v|coscos + |u||v|sinsin
= |u||v|(coscos + sinsin)
= |u||v|(cos(-)
= |u||v|cos
