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Math Help - cos x

  1. #1
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    cos x

    I would appreciate if someone helps with this problem. Thanks.


    Tom and Jerry use their calculators to calculate cos x. Tom enters x as x degrees, while Jerry enters x radians. Tom gets an answer y, while Jerry gets the value -y. Let x be the smallest positive value for which this happens. Find x.
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  2. #2
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    Quote Originally Posted by chil2e View Post
    I would appreciate if someone helps with this problem. Thanks.


    Tom and Jerry use their calculators to calculate cos x. Tom enters x as x degrees, while Jerry enters x radians. Tom gets an answer y, while Jerry gets the value -y. Let x be the smallest positive value for which this happens. Find x.
    1. Let r denote the value of an angle in radian and d the value of the same angle in degree. Then the conversion of degree into radian is calculated by:

    r = \dfrac d{180} \cdot \pi

    2. If the angle x is measured in degree the cos-function has the property

    \cos(x) =- \cos(180^\circ - x)

    3. According to the text of the question you have to solve the equation for x:

    x = \dfrac{180-x}{180} \cdot \pi

    4. I've got x \approx 3.087702086...
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  3. #3
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    That is a better and more correct approach. Touche.
    Last edited by abender; January 12th 2010 at 11:15 PM.
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