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Math Help - Archimedes spiral?

  1. #1
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    Archimedes spiral?

    Can anyone show how to graph which is an Archimedes spiral?

    r=3(theta)
    How would I graph this
    I mean I know theta is the angle So would I say 3 times 30 degrees r is 90?
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  2. #2
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    Quote Originally Posted by homeylova223 View Post
    Can anyone show how to graph which is an Archimedes spiral?

    r=3(theta)
    How would I graph this
    I mean I know theta is the angle So would I say 3 times 30 degrees r is 90?
    Normally the Archimede's spiral is given with theta in radians, not degrees. So at theta= 0, you mark the origin, r= 0. At 45 degrees- halfway between the positive x and y axes, \theta= \pi/4 and r= 3\pi/4. At 90 degrees, along the positive y- axis, \theta= \pi/2 and r= \3\pi/4, etc. However, using degrees rather than radians would only change the scale, not the shape.
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  3. #3
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    Wouldn't r = \dfrac{3\pi}{2} at \theta = \dfrac{\pi}{2}?
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  4. #4
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    Yes, that was what I thought I wrote!
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  5. #5
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    Hmm the only confusion I am having in that checking the answer in the back of my book r is 5 10 15 20. I mean your answer makes sense I just do not see why r in my book would be 5 10 15 20 in the polar graph?
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