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Math Help - Confused in radians

  1. #1
    Senior Member Paze's Avatar
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    Confused in radians

    I am converting some radians to degrees. I would assume that sin(1°) = sin(pi/180) yes? Since 1°=pi/180. So by algebraic defaults, this should hold true..

    But I am getting strange values in these three calculations:
    sin-356° - Wolfram|Alpha

    sin4° - Wolfram|Alpha

    sin364° - Wolfram|Alpha

    They all state that the respected degrees equal pi/45 rad..

    To my knowledge, \frac{\pi}{45}=4\deg which holds true for the 2nd calculation in my row there.

    However, if I convert 364 degrees to radians I do it like this: 1deg=\frac{\pi}{180} so 364deg=\frac{364\cdot \pi}{180} which I do not understand how becomes \frac{\pi}{45}

    It's probably just some fundamental issue that I am overlooking as usual, but I would appreciate some direction here. Thanks.
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  2. #2
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    Re: Confused in radians

    When a ray starts from x axis and rotates in anticlockwise direction and completes one round it covers 360 degree or 2 pi radian. in case the angle is more than 360 degree or 2 pi we just consider the angle between 0 and 360 degree or 0 and 2 pi. For example if we have 390 degree we consider 390 -360 = 30 degree only. Further we know that angle measured in clockwise direction is considered negative. Thus if we have angle 356 degree it is the same as -4 degree and 364 degree is the same as 4 degree.
    Thanks from Paze
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  3. #3
    Senior Member Paze's Avatar
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    Re: Confused in radians

    Quote Originally Posted by ibdutt View Post
    When a ray starts from x axis and rotates in anticlockwise direction and completes one round it covers 360 degree or 2 pi radian. in case the angle is more than 360 degree or 2 pi we just consider the angle between 0 and 360 degree or 0 and 2 pi. For example if we have 390 degree we consider 390 -360 = 30 degree only. Further we know that angle measured in clockwise direction is considered negative. Thus if we have angle 356 degree it is the same as -4 degree and 364 degree is the same as 4 degree.
    Ah, I see. Thanks.
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