# Homework Help: Quick question: Really easy

1. Jan 30, 2008

### Cursed

Can two nonzero perpendicular vectors be added together so their sum is zero?

I want to say yes, but I'm not sure. :uhh:

2. Jan 30, 2008

### Staff: Mentor

Thread moved to Homework Help. What are your thoughts, Cursed? Why are you inclined to say yes, and how do you think you could go about proving it? Have you studied orthonormal bases yet? What does the term perpendicular (or orthogonal) imply?

3. Jan 30, 2008

### Cursed

No, I haven't studied orthonormal bases yet. That's probably why I don't understand it. :tongue:

I figured that one vector could cancel out the other provided that both their magnitudes are equivalent, and if one vector component is negative while the other one is positive.

4. Jan 30, 2008

### Staff: Mentor

Think about what the term perpendicular (orthogonal) means. One set of perpendicular vectors would be (0,1) and (1,0), for example. Or the two vectors could be rotated together to any angle in the x-y plane, but still in the perpendicular position. Write some equations that would define two orthogonal vectors....do you see anything special?

5. Jan 31, 2008

### HallsofIvy

Have you considered drawing a picture? Draw two perpendicular vectors. There sum can be found using the "parallelogram law" which, in the case of perpendicular vectors is a "rectangle". Can you find a rectangle, with non-zero sides that has a diagonal of length 0?