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    i bet this is a relli easy question but the book doesnt quite tell me how to do it.

    The vector p has magnitude 10 units and is inclined at 150 degrees to the x-axis. Express p as a column vector.

    i no that the values are 5 root3 and 5, but i dont no which is negative and positive.

    help???:confused:
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    Draw a diagram. It's inclined at 150 degrees (anticlockwise) to the (positive) x-axis. Which quadrant of your graph is it in?
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    i think its in the second quadrant (without drawing)? does that tell u which bit is negative n positive?
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    (Original post by blacklashes)
    i think its in the second quadrant (without drawing)? does that tell u which bit is negative n positive?
    Yes.

    cos describes x and sin describes y, hence in the second quadrant you are above the x axis, hence cos is positive and you are to the left of the y axis, hence sin is negative. Sorry for the crap explanation
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    (Original post by blacklashes)
    i think its in the second quadrant (without drawing)? does that tell u which bit is negative n positive?
    Well... yes. Draw the vectors (5 root 3, 5), (-5 root 3, 5), (5 root 3, -5), (-5 root 3, -5), and you'll see which one it is.
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    thanks it alls cleared up now!!! +
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    im not sure how to do this question...

    Given that the points A and B are (3,5) and (1,10) respectively, find a vector equation for the line through the point A and perpendicular to B.
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    (Original post by blacklashes)
    im not sure how to do this question...

    Given that the points A and B are (3,5) and (1,10) respectively, find a vector equation for the line through the point A and perpendicular to B.
    Perpendicular to a point?:confused:

    Surely this isn't the correct question :P
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    (Original post by coffeym)
    Perpendicular to a point?:confused:

    Surely this isn't the correct question :P
    I assume it means perpendicular to the line AB.
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    Could mean perpendicular to b.

    Clarification please?
 
 
 
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