Results 1 to 2 of 2

Thread: [SOLVED] Two simple problems

  1. #1
    Senior Member Spec's Avatar
    Joined
    Aug 2007
    Posts
    318

    [SOLVED] Two simple problems

    You're not supposed to use vector/scalar multiplication tricks for these problems.

    1) The point C divides the vector AB in the ratio 1:3. Show that $\displaystyle \overline{OC} = \frac{3}{4}\overline{OA} + \frac{1}{4}\overline{OB}$

    2) $\displaystyle u,\ e_1,\ e_2$ are in the same plane.

    $\displaystyle |u| = 2, |e_1| = 2, |e_2| = 1$
    The angle between $\displaystyle e_1$ and $\displaystyle e_2$ is $\displaystyle \frac{2\pi}{3}$, and $\displaystyle \frac{\pi}{6}$ between $\displaystyle u$ and $\displaystyle e_1$.

    Write $\displaystyle u$ as a linear combination of $\displaystyle e_1$ and $\displaystyle e_2$.

    Note that this will give two possible answers.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member Spec's Avatar
    Joined
    Aug 2007
    Posts
    318
    1)

    $\displaystyle \overline{AB} = \overline{OB} - \overline{OA}$

    $\displaystyle \overline{OC} = \overline{OA} + \frac{1}{4}\overline{AB}$

    $\displaystyle \overline{OC} = \overline{OA} + \frac{1}{4}(\overline{OB} - \overline{OA}) = \frac{3}{4}\overline{OA} + \frac{1}{4}\overline{OB}$
    Last edited by Spec; Aug 25th 2008 at 07:16 AM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Indices (simple but i am have problems)
    Posted in the Algebra Forum
    Replies: 1
    Last Post: Jan 8th 2012, 09:34 AM
  2. few simple limit problems :D
    Posted in the Calculus Forum
    Replies: 6
    Last Post: Apr 26th 2011, 08:11 AM
  3. Simple Economics Problems.
    Posted in the Math Topics Forum
    Replies: 0
    Last Post: Feb 2nd 2010, 01:13 PM
  4. Help with simple microeconomic problems
    Posted in the Business Math Forum
    Replies: 0
    Last Post: Nov 18th 2009, 03:02 PM
  5. help with a few simple problems..
    Posted in the Algebra Forum
    Replies: 8
    Last Post: May 10th 2007, 08:46 AM

Search Tags


/mathhelpforum @mathhelpforum