help with vectors

Discussion in 'Math' started by Omega, Apr 20, 2009.

  1. Omega

    Thread Starter Member

    Feb 23, 2009
    15
    0
    Hello every one I have this vector relation
    E=A+\alpha(HXA) where E,A and H are vectors I want to proof that A=(E-\alpha(HXA))/\sqrt{1+H^{2}\alpha^{2}}
    any one remeber how we can do this using vector identities or simple geometry or both of them (may be)?
     
  2. Ratch

    New Member

    Mar 20, 2007
    1,068
    3
    Omega,

    Just so there is not doubt, define what the capital H and alpha, both under the square root sign mean.

    Ratch
     
  3. Mark44

    Well-Known Member

    Nov 26, 2007
    626
    1
    Starting with E=A+\alpha(HXA),
    subtract \alpha(HXA) from both sides, which gives you
    A=(E-\alpha(HXA))

    I have no idea how you got the radical in there that you show.
     
  4. Omega

    Thread Starter Member

    Feb 23, 2009
    15
    0
    sorry the correct equation is A=(E-[​IMG](HXE))/(1+\alpha^{2}H^{2}) I am realy sorry for this mistake. both of E and H are vectors with magnitudes E and H respectively and \alpha is just a constant
    I tried the method of Mark44 but it did not give me the factor 1/(1+\alpha^{2}H^{2})
     
  5. Ratch

    New Member

    Mar 20, 2007
    1,068
    3
    Omega,

    Is this correcting the first or the second equation of your problem? You really should completely restate the problem after checking it carefully for typos and other errors so we don't have to guess what it means.

    Ratch
     
  6. Omega

    Thread Starter Member

    Feb 23, 2009
    15
    0
    ok from the begining: it is given that E=A+[​IMG](HXA) I need to proof the expression:
    A=(E-[​IMG](HXE))/(1+[​IMG][​IMG]H[​IMG]) where A, E, and H are vectors and H is the magnitude of H and [​IMG] is just a constant
     
  7. Ratch

    New Member

    Mar 20, 2007
    1,068
    3
  8. Omega

    Thread Starter Member

    Feb 23, 2009
    15
    0
    yes I did thanks.
     
  9. killerfish

    Member

    Feb 27, 2009
    17
    4
    Hi guys,

    currently im teaching myself vector, any of u guys could recommend good online sites that teach vectors from stretch to advance? I did a google around, i couldnt find any site cover in-depth/details about it rather just brief one. And I couldnt get any course notes to help me.:( Hope u guys lent me a hand.

    Thanks.
     
    Last edited: Jun 1, 2009
  10. Omega

    Thread Starter Member

    Feb 23, 2009
    15
    0
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