## Vector operations

1. The problem statement, all variables and given/known data
Let x and y be to vectors
Verify whether |xy|<=|x|+|y| for all x,y

3. The attempt at a solution
My first problem with this question is that it does not tell us whether the operation xy is the same as x.y (dot product) or a cross product.

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 Recognitions: Gold Member Science Advisor Staff Emeritus Your are right. That is a problem. I am also surprised that is not $|x|^2+ |y|^2$ on the right. I suspect that they mean dot product. I suggest you look at $|(x-y)\cdot(x-y)|$.