# Cosine of a vector.

1. Feb 6, 2014

### Tiven white

1. The problem statement, all variables and given/known data
The cosine of a vector is equal to the opposite over its magnitude.

2. Relevant equations

The attempt at a solution[/b] the cosine is the ratio of the adjacent to the hypothenuse this is why i say it "came' is incorrect.

2. Feb 7, 2014

### haruspex

What exactly was the original question?

3. Feb 7, 2014

### Tiven white

That is the ?,its a true or false

4. Feb 7, 2014

### Staff: Mentor

What statement is true or false?

Oh, I see. It's this statement that's being questioned:
Yes, it's an incorrect statement, as you pointed out.

Last edited: Feb 7, 2014
5. Feb 7, 2014

### Tiven white

If the cosine of a vector is its y component over its magnitude?

6. Feb 7, 2014

### Staff: Mentor

It's not the vector which has a cosine. It's only angles which have cosines.

7. Feb 7, 2014

### HallsofIvy

Staff Emeritus
If this really is the statement, I would not say it was either "true" or "false". I would just say it is non-sense! The function "cosine" is not [g]defined[/b] for vectors, only for angles or numbers. Further, saying "the opposite" is non-sense. "Opposite" is an adjective not a noun and cannot take the article "the".

8. Feb 7, 2014

### vela

Staff Emeritus
Just out of curiosity, what is
supposed to mean?

9. Feb 7, 2014

### Staff: Mentor

cosine = adjacent ÷ magnitude ?

10. Feb 7, 2014

### vela

Staff Emeritus
Wouldn't that be correct?

11. Feb 7, 2014

### Staff: Mentor

Clearly, OP is a little confused.

12. Feb 7, 2014

### Tiven white

cosine

The question was asking whether the statement ' cosine means the y component of a vector over its magnitude'.
Is this true or false?

13. Feb 7, 2014

### Staff: Mentor

Definitely false.