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Math Help - Converting polar coordinates.

  1. #1
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    Converting polar coordinates.

    Absolutely lost on this:

    r=8cotx (x should be in degrees).

    I tried converting this (as well as others) but I seem to just get nowhere after I turned cot into cosx/sinx.

    Thanks.

    Edit: The equation above should be converted to rectangular form.
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  2. #2
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    Quote Originally Posted by Cheagles View Post
    Absolutely lost on this:

    r=8cotx (x should be in degrees).

    I tried converting this (as well as others) but I seem to just get nowhere after I turned cot into cosx/sinx.

    Thanks.

    Edit: The equation above should be converted to rectangular form.
    \sqrt{x^2 + y^2} = 8 \, \frac{\frac{x}{r}}{\frac{y}{r}} = 8 \, \frac{x}{y}

     \Rightarrow x^2 + y^2 = 64 \, \frac{x^2}{y^2}

    \Rightarrow y^2 (x^2 + y^2) = 64 x^2.
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  3. #3
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    I think I would have done this a slightly different way:

    r= 8 cot(\theta)= 8\frac{cos(\theta)}{sin(\theta)} so
    r sin(\theta)= 8 cos(\theta)
    Multiplying on both sides of the equation by r,
    r(r sin(\theta))= 8 r cos(\theta)
    and
    \sqrt{x^2+ y^2}y= 8x
    Now squaring both sides will give what Mr. fantastic got.
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