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Math Help - [SOLVED] Value of trigonometric expression?

  1. #1
    Super Member fardeen_gen's Avatar
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    [SOLVED] Value of trigonometric expression?

    The value of sin(1/2.arccot(-3/4)) + cos (1/2.arccot(-3/4)) is equal to:

    A)1
    B)(3√20)/10
    C)√2.sin ((3π/4) + 1/2.arccot 3/4)
    D)√2.sin(π -1/2.arccot 4/3)

    More than one options may be correct.
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  2. #2
    MHF Contributor
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    How far have you gotten?

    1) Remember that arccot(x) produces an ANGLE, usually on (0,\pi).
    2) Do you have half-angle formulas? You will need them.
    3) There are some right triangles in your future.
    4) Don't forget what Quadrant you are in. (Actually, you tell me if this matters. Maybe symmetry will bail you out.)
    Last edited by TKHunny; September 25th 2008 at 06:16 AM. Reason: Minor Expansions
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  3. #3
    Super Member fardeen_gen's Avatar
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    The given expression equals √(1 4/5). Which gives B,C and D as the answers.
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