1. ## combining vectors

if a=<1,-1,2> b=<3,2,1> and c=<3,1>

is it possible to add (a+c) or |a|+ |c| ?

is it possible to do: (a dot a) x b ?

2. Originally Posted by cottekr
if a=<1,-1,2> b=<3,2,1> and c=<3,1>

is it possible to add (a+c) or |a|+ |c| ? No, Yes
is it possible to do: (a dot a) x b ? No
Vectors need to be the same dimension to add them or take the cross product or dot product of them. $|a|$ and $|c|$ are both real numbers, so adding them is fine.