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Section 1.3

By cssp

Please post comments if you find any errors, or if you wish to contribute answers for additional problems. You may find information on using \LaTeX here.

1. (a) \mathbf{x} \times \mathbf{y} = (1, 3, 7)

(b) \mathbf{x} \times \mathbf{y} = (-2, 16, -5)

(c) \mathbf{x} \times \mathbf{y} = (36, -12, 0)

(d) \mathbf{x} \times \mathbf{y} = (-6, 2, -14)

3. 11

5. 3

7. \dfrac{9}{2}

9. 42

13. For example, \mathbf{e}_2 \times \left(\mathbf{e}_2 \times \mathbf{e}_3\right) = -\mathbf{e}_3 , whereas \left(\mathbf{e}_2 \times \mathbf{e}_2\right) \times \mathbf{e}_3 = \mathbf{0} .

This entry was posted on 22 June 2007 at 1:03 pm and is filed under Section 1.3. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

2 Responses to “Section 1.3”

  1. Geran Says:
    27 January 2008 at 8:54 pm | Reply

    I could well be wrong, but I think 1(c) and 7 are incorrect.

    For 1(c) x=(1,3,-2) and y=(3,9,6) then x cross y = (18+18, -6-6, 0).

    For 7 the points are (-1,2), (2,-1) and (1,3) => two vectors are (2,1) and (3,-3) and their cross-product is 9. Thus Area = 4.5 not 6.5

    Sorry if my answers are wrong.

  2. cssp Says:
    27 January 2008 at 9:46 pm | Reply

    You are right. I have made the corrections above.

    Thanks.

    Dan Sloughter

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