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Homework Help: Trig transformation?

  1. Oct 11, 2007 #1
    1. The problem statement, all variables and given/known data

    A point with coordinates x and y is rotated in an anticlockwise direction through an angle z, so that its distance from the origin of the coordinate system remains constant. Show that the new x and y coordinates become

    xcosz - ysinz and xcosz + ysinz respectively.

    2. Relevant equations

    3. The attempt at a solution

    Well im looking for some advice on how to start this! The wording is confusing to me! To my mind surely if you rotate a point it will be exactly the same??? Any help would be supremely appretiated.
  2. jcsd
  3. Oct 11, 2007 #2


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    By rotating a point, they mean it is rotated about the origin by a angle z. start by drawing a picture, show the x and y components at each location. Now study the pic until you can identify the relationships.
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