1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Vector help!

  1. Feb 9, 2013 #1
    1. The problem statement, all variables and given/known data
    I cannot find other sources to help me with this problem set, I have A B and C vectors defined by: A (2,1,1) B(1,-1,0), C(-1,1,-1)
    From these I have a list of questions and some I am stuck on are:each of these are vectors with an arrow above it
    1. |A| + |B| this I did as √ax^2 +ay^2 +az^2 + √the same for B
    2. |A + B| but how do i do this, what is the difference between these?

    3. A + B

    4. 3C

    5. A dot (B X C)

    8. What is the angle between A and B, A and C, and B and C? in radians use pi

    id appreciate any help!!
  2. jcsd
  3. Feb 9, 2013 #2


    User Avatar
    Homework Helper

    This would be correct.

    This is asking for you the magnitude of (vector A + vector B), question 1 was asking you for the magnitude of vector A + the magnitude of vector B. Start by first calculating what A+B is, how do you add two vectors together?

    The same as question 2.

    Do you know how to multiply a vector by a scalar?

    Do you know the terms 'dot product' and 'cross-product'?

    This question depends on if you can do question 5.
  4. Feb 10, 2013 #3
    Wikipedia explains the basic properties of vectors such as addition, scalar multiplication, length as well as dot and cross products.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook