Vector Squared: Solving for c in (a + b)^2 = c with Vectors

[MadMax]

If I have (a + b)^2 = c, where a and b are vectors, is c = a^2 + 2(a . b) + b^2, or simply is c=a^2 +b^2 + 2ab?

My motivation behind considering the former is that q^2 = q.q, however my motivation behind considering the latter is that if I have q^2=c then it does not matter whether q ia a vector or not, c is the same...

:/

 

[malawi_glenn]

Yes the a b should be dot product.

|a|*|b|cos(w) w is angle between a and b.

so: c = (a + b) ^2 = [a|^2 + |b|^2 + 2|a|*|b|cos(w)

 

[MadMax]

thanks malawi :)

 

[malawi_glenn]

np good luck!

ps. this is not a home work question in "Advanced physics" , but in precalclus maths hehe

 

[MadMax]

Oh yeah you are right, sorry about that. I didn't realize there was such a section in the forums :) thanks for the heads up.