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    Hate vectors so much. This is the forst exercise in my book and I can't seem to do it. There aren't any examples on how to do it either:

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

    Any help is appreciated as I am lost, thanks.
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    (Original post by mnaj123)
    Hate vectors so much. This is the forst exercise in my book and I can't seem to do it. There aren't any examples on how to do it either:

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

    Any help is appreciated as I am lost, thanks.
    Draw a triangle with one vertex at the origin, a hypotenuse with length ten and the angle 30 degrees marked in between the negative x-axis and the hypotenuse. Then calculate the height \sin 30^{\circ} = \frac{y}{10} and that's your \mathbf{j} component. The length of the adjacent or base will be your \mathbf{i} component but you will need to tack on a minus sign for obvious reasons.
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    (Original post by Zacken)
    Draw a triangle with one vertex at the origin, a hypotenuse with length ten and the angle 30 degrees marked in between the negative x-axis and the hypotenuse. Then calculate the height \sin 30^{\circ} = \frac{y}{10} and that's your \mathbf{j} component. The length of the adjacent or base will be your \mathbf{i} component but you will need to tack on a minus sign for obvious reasons.
    Ahhhh thanks so much! Got it..
    But, how do I know when to use the angle given or 180-given angle?
    Because most of these question require you to use the given angle rather than 180-it.

    Thanks for your help.
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    (Original post by mnaj123)
    Ahhhh thanks so much! Got it..
    But, how do I know when to use the angle given or 180-given angle?
    Because most of these question require you to use the given angle rather than 180-it.

    Thanks for your help.
    Not a problem, glad that helped - uhm, basically just sketch the triangle and see what angle makes life the easiest. :-)
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    (Original post by Zacken)
    Not a problem, glad that helped - uhm, basically just sketch the triangle and see what angle makes life the easiest. :-)
    Aha, alright thank you so much
 
 
 
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