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Homework Help: Polar coordinates

  1. Sep 18, 2011 #1
    1. The problem statement, all variables and given/known data
    Hi, I have the coordinates of an "expression" for a point in a cartesian coordinate system. I'm trying to write it in a polar coordiante system (in function of r and theta) but I don't know how to find the answer

    a = y-component of the point
    b = x-component of the point
    theta = angle between the y-axis and a line connecting the point with the origin
    r = distance from the origin till the point


    2. Relevant equations

    the expression which I would like to write in a polar coordinate system is:

    a.sin(theta) + b.cos(theta)

    The result should be:

    r.sin(theta).cos(theta)

    How to get to this result?

    3. The attempt at a solution
     
  2. jcsd
  3. Sep 18, 2011 #2
    Start off drawing your unit circle. You should be able to figure it out from there. If you can't figure out the transform, trying looking up coordinate transforms on wikipedia. I know they have a good page on the topic.

    If you have a problem understanding where the transforms come from or how to use them, try going over some examples in a text book or drawing the vectors. This is something one really needs to understand to perform well in physics.
     
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