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Math Help - Arc Length

  1. #1
    Super Member craig's Avatar
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    Arc Length

    Just a quick question.

    Is the arc length L of a circle with radius r, made by the angle \theta, L = r \theta or L = 2r \theta?

    Measuring \theta in radians obviously.

    Thanks
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    Quote Originally Posted by craig View Post
    Just a quick question.

    Is the arc length L of a circle with radius r, made by the angle \theta, L = r \theta or L = 2r \theta?

    Measuring \theta in radians obviously.

    Thanks
    When the radius vector completes one rotaτion, it covers an angle 2π radians. The tip of the vector moves through a distance 2πr.
    So when the distance moved by tip is L, what the angle covered by the vector?
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  3. #3
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    Quote Originally Posted by craig View Post
    Just a quick question.

    Is the arc length L of a circle with radius r, made by the angle \theta, L = r \theta or L = 2r \theta?

    Measuring \theta in radians obviously.

    Thanks
    Which one gives the correct circumference ( \theta = 2 \pi) ....?
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    Super Member craig's Avatar
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    Thanks for the replies, not sure what happened then, just couldn't visualise it at all

    Arc length L = r \theta

    Cheers for that
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