# Cosine of a vector.

## Homework Statement

The cosine of a vector is equal to the opposite over its magnitude.

## Homework 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.

haruspex
Homework Helper
Gold Member
2020 Award
What exactly was the original question?

What exactly was the original question?
That is the ?,its a true or false

NascentOxygen
Staff Emeritus
That is the ?,its a true or false
What statement is true or false?

Oh, I see. It's this statement that's being questioned:
The cosine of a vector is equal to the opposite over its magnitude.

Yes, it's an incorrect statement, as you pointed out.

Last edited:
What statement is true or false?

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

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

HallsofIvy
Homework Helper

## Homework Statement

The cosine of a vector is equal to the opposite over its magnitude.
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".

## Homework Equations

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

vela
Staff Emeritus
Homework Helper
Just out of curiosity, what is
this is why i say it "came' is incorrect.
supposed to mean?

NascentOxygen
Staff Emeritus
Just out of curiosity, what is
[ C A M ]
supposed to mean?

cosine = adjacent ÷ magnitude ?

vela
Staff Emeritus
Homework Helper
Wouldn't that be correct?

NascentOxygen
Staff Emeritus
Wouldn't that be correct?
Clearly, OP is a little confused.

cosine

Clearly, OP is a little confused.

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

NascentOxygen
Staff Emeritus