# Homework Help: Never seen vectors before

1. May 26, 2012

### synkk

Could anyone explain to me what all these notations are for the vectors? I've never used vectors before and all I know is that they show direction and magnitude, but don't know the actual notation. I'm assuming OA is the vector of O to A but what is it when they put the modulus around the vector?

Any links to vectors would be great, thanks.

2. May 26, 2012

### Staff: Mentor

That indicates the magnitude of the vector.
Basic Vector Operations

3. May 26, 2012

### synkk

I see, for the magnitude you just use Pythagoras to find it? Could you not use the distance between two points?

4. May 26, 2012

### Staff: Mentor

Yes.
That amounts to the same thing.

5. May 26, 2012

### mtayab1994

The formula for finding the magnitude is :

$$|a|=\sqrt{a_{1}^{2}+a_{2}^{2}}$$

6. May 26, 2012

### e^(i Pi)+1=0

hint: the absolute value of a complex number, just like any number, is its distance from zero...

7. May 26, 2012

### synkk

I'm not sure what A is.

Okay for this sketch:

Vector OB is 2(34)^1/2
Vector OA is 13

Now i'm reading about vectors online and it's saying that you can get to point A from OB, then to A. Now the distance from B to A is root 5, so OB to B-A should be the same as OA? Well If I add root 5 and 2(34)^1/2 it is not 13. Could anyone clear this up thanks.

8. May 26, 2012

### azizlwl

Basic calculation
Use a graph paper and draw the vectors to scale.
From this drawing you can find the magnitude of vector AB

Later you will be able to use vector algebra to calculate the magnitude and direction.
http://emweb.unl.edu/math/mathweb/vectors/vectors.html

Last edited: May 26, 2012
9. May 27, 2012

### Staff: Mentor

It's true that the vector sum of $\vec{OB} + \vec{BA} = \vec{OA}$. But you don't add vectors by simply adding their magnitudes. To learn how to add vectors (there are several ways) explore the link I gave you earlier and this one: Vector Addition.