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  • Nov 4, 2008, 05:44 PM
    klandard
    exact values of trig. Functions
    I need help with this Precal problem

    find all the exact t- values for which sin t = -1/2
    I need to show work also so any steps would be helpful!!
  • Nov 5, 2008, 12:13 AM
    Unknown008

    We're not supposed to DO your work. I'll therefore give you an example instead.

    If you had cos x = 1, then



    And the answers would be

    | /
    S | A
    ____|/____
    |\
    T | C
    | \

    In 'A' and 'C', ( meaning all positive and cos positive)

    First angle is 90 degrees, you get it directly.
    The second is 270, because 360 - 90 = 270 degrees.

    Therefore, x would equal 90 and 270 degrees. (note that the angle you have is between the diagonal and the horizontal line)
    ---------

    If you had cos x = -1, then



    And the answers would be

    \ |
    S | A
    ___\|_____
    /|
    T | C
    / |

    In 'S' and 'T', ( meaning tan positive and sine positive) since you had cos x = -1 and if it is negative, it cannot be all positive nor cos positive.

    First angle is 90 degrees, you get it by 180 - 90 = 90 degrees
    The second is 270, because 180 + 90 = 270 degrees.

    Therefore, x would equal 90 and 270 degrees.
    -----------

    If you had sin x = 0, then



    And the answers would be

    \ | /
    S | A
    ___\|/____
    |
    T | C
    |

    In 'A' and 'S', ( meaning all positive and sine positive)

    First angle is 0 degrees, you get it directly.
    The second is 180, because 180 - 0 = 180 degrees.
    The third is 360 because 360 - 0 = 360 degrees.

    Therefore, x would equal 0, 90 and 360 degrees.
    ----------

    I know it's a bit confusing at first, so don't hesitate to outline the parts you don't understand.

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