## unit vectors

1. The problem statement, all variables and given/known data
Vector A=3i-1j and B=-i-4j
Find vector A-B and|vector A-B|

2. Relevant equations

3. The attempt at a solution

Vector A-B=4i-3j

Is the |vector A-B|the magnitude or just the absolute value of the answer?

Thank you very much

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 Recognitions: Gold Member |A| is the magnitude of a vector A. To avoid confusion, one can use ||A|| to denote magnitude.
 Thank you very much Is the other part correct? The magnitude is the same thing as the angle of the vector, right? Is there a formula for calculating the magnitude? Thank you

Recognitions:
Gold Member

## unit vectors

The magnitude of a vector whose components are <a1, a2> (2 dimensional vector) is:

$$\sqrt{a_1^2 + a_2^2}$$
Please do not confuse magnitude and direction. Although they are both characteristics of a vector, they are different things.

Recheck A-B, the j component has its sign messed up.

 Thank you very much 4i+5j does that look correct?
 Recognitions: Gold Member Recheck. Let A = and B = A-B =
 If vector A=3i-1j and B=-1i-4j in order to find A-B, don't you just do 3i--1i=4i and -1i--4j=3j Wouldn't it be 4i+3j? and is the magnitude of A-B 6.40? Thank you
 Recognitions: Gold Member Yup 4i+3j is correct. You made the mistake of writing 4i-3j in your initial post.
 Thank you very much Regards
 Recognitions: Gold Member But your magnitude doesnt look too good. Recheck that.
 Thank you