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    cowboys93's Avatar
    cowboys93 Posts: 9, Reputation: 1
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    #1

    Aug 9, 2009, 05:00 PM
    Law of sines
    welli was given a triangle wit a=36 degrees
    a=8
    b=5

    and I did sin b and it was .3673
    but then next to it is an error and it is equal to 21.6
    how did they get 21.6?
    I am trying to figure this out on a graphing calculator but I don't know how after .3673 they got 21.6

    helppp.thanks.
    ArcSine's Avatar
    ArcSine Posts: 969, Reputation: 106
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    #2

    Aug 9, 2009, 05:22 PM
    Well, you're correct so far. Based on the given info and the Law of Sines, the sine of Angle B is 0.3673, just as you've figured.

    But to wrap up, you need to find the measure of Angle B such that sin(B) = 0.3673. Then you can call it a day.
    cowboys93's Avatar
    cowboys93 Posts: 9, Reputation: 1
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    #3

    Aug 9, 2009, 05:24 PM
    Quote Originally Posted by ArcSine View Post
    Well, you're correct so far. Based on the given info and the Law of Sines, the sine of Angle B is 0.3673, just as you've figured.

    But to wrap up, you need to find the measure of Angle B such that sin(B) = 0.3673. Then you can call it a day.
    How do u find that measure?
    Cause I've been trying to figure that out and I can't on the graphing calculator
    ArcSine's Avatar
    ArcSine Posts: 969, Reputation: 106
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    #4

    Aug 9, 2009, 05:31 PM
    It's the inverse sine function, and on many calculators it's denoted by the key .

    Being the inverse of the sine function, it takes a sine value as the input argument, and returns the angle measure which has that value for its sine.

    For example, since sin(36) is approx 0.5878, then (0.5878) = 36 (degrees).

    Good to go?
    Unknown008's Avatar
    Unknown008 Posts: 8,076, Reputation: 723
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    #5

    Aug 10, 2009, 09:24 AM

    It's good to know that is also known as :D
    ArcSine's Avatar
    ArcSine Posts: 969, Reputation: 106
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    #6

    Aug 10, 2009, 10:50 AM
    Yep, the former Mrs. ArcSine used to say that I was an inverse function--I never knew quite how to take that.

    Of course, she also used to remind me daily that the Law of Sines was this: Around the Sine household, whatever she says is law.

    No complaints from me, though, what with her intoxicating sine curves and harmonic motion... ;)
    Unknown008's Avatar
    Unknown008 Posts: 8,076, Reputation: 723
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    #7

    Aug 10, 2009, 10:56 AM

    LMAO! :p

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