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Homework Help: Bit of a problem with polar coordinates.

  1. Feb 9, 2006 #1
    Bit of a problem with polar coordinates. (Only trig knowledge needed.)

    Right. So, in this problem, I'm given the polar coordinate point (rad2, 4.39) -- "rad2" being, naturally, short for radical 2. I'm to find the rectangular coordinates of the point, using the formulas:

    x = r cos Theta

    and y = r sin Theta. In this problem, r = rad2 and Theta = 4.39.

    Simple, no? Only for some reason, it's not coming out right with my calculator. I substitute the givens, for:

    x = rad2 * (cos 4.39)

    and y = rad2 * (sin 4.39).

    I have the answers -- they're in the back of the textbook -- but can't figure out the process. x should equal approx. -0.45, and y should equal -1.34. Instead, I find x to equal 1.41 and y to equal 0.11. Am I doing something in the wrong order?

    Any help is appreciated. Thanks. ; )
    Last edited: Feb 9, 2006
  2. jcsd
  3. Feb 9, 2006 #2
    Are you sure your calculator is in radian mode and not degree mode if the 4.39 is inradians?
  4. Feb 9, 2006 #3
    Actually, no. I hadn't thought of that. But I don't know how to set it in radian mode. Is there some way I could convert the 4.39 into a form usable in degree mode?
  5. Feb 10, 2006 #4
    Multiply by 180/pi.
  6. Feb 10, 2006 #5
    . . . . . . . .

    *smacks forehead*

    I can't believe I missed that. Thanks so much.
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