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Math Help - Solving trigo

  1. #1
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    Solving trigo

    cos3X=sinX

    Find X, 0 degree < x < 360 degree

    Thanks in advance
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  2. #2
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    Quote Originally Posted by ose90 View Post
    cos3X=sinX

    Find X, 0 degree < x < 360 degree

    Thanks in advance
    There's the hard way and the easy way. Personally I like the easy way best:

    From the complementary angle formulae: \cos (3x) = \sin x \Rightarrow \cos (3x) = \cos (90 - x).

    Case 1: 3x = 90 - x + 360 n where n is an integer.

    Solve for x and substitute appropriate values of n to get all values of x satisfying the given domain.


    Case 2: 3x = -(90 - x) + 360 n where n is an integer.

    Solve for x and substitute appropriate values of n to get all values of x satisfying the given domain.
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  3. #3
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    Thank you very much!
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