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    Orpheo's Avatar
    Orpheo Posts: 1, Reputation: 1
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    #1

    Feb 21, 2014, 10:55 PM
    sin (-105°) Find the exact value of this expression.
    Find the exact value of this expression:

    sin (-105°)


    I've found multiple solutions online for sin (105°) but not sin (-105°), please help.
    Please show work if possible. I'm getting right numbers but my positive / negative symbols are off and I don't know why.
    ebaines's Avatar
    ebaines Posts: 12,131, Reputation: 1307
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    #2

    Feb 22, 2014, 08:35 AM
    You should know that .
    InfoJunkie4Life's Avatar
    InfoJunkie4Life Posts: 1,409, Reputation: 81
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    #3

    Feb 22, 2014, 08:52 AM
    Don't quote me, but this might work...




    you could use

    and since sin(0)=0 and cos(0)=1



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