Recent content by Elektrykia

Haha, oh wow, I looked over that like four times. For some reason ab looked so wrong to me when I got it, I understand it now. Thanks very much (:

(a+b) dot (a+b) = a^2 + b^2 + 2ab, yes?

I've tried that, maybe there's something I'm missing but I do v=a+b and u=a-b and get them to a point where i can expand them out and I get 1/4ab as the answer.

Homework Statement Show that the dot product of vectors a and b is equal to 1/4|a+b|^2 - 1/4|a-b|^2 Homework Equations a dot b = |a||b|cos(theta) a dot b = a1b1 + a2b2 + ... The Attempt at a Solution I've tried using the combination of the cosine law and those two above dot...