5. Which of the vectors


are orthogonal to the vector

and have length less than 4?

A. y onlyB. z only C. x and y only D. x and z only E. None of these

Solution: The answer is D.

Recall, two vectors are orthogonal if and only if their dot product is 0. By inspection each of x, y, and z is orthogonal to v. Furthermore


So, x and z are the only vectors satisfying both conditions.