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without using a calculator write down the values of sin(-90), tan(-180) watch

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    how can i work it???? i know how to calculate using a graph but idk the other method the quadrant i could express using the quadrant
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    (Original post by hujikolp)
    how can i work it???? i know how to calculate using a graph but idk the other method the quadrant i could express using the quadrant
    You need to know how the sin, cos and tan graphs look like. They're periodic so if you know the basic shape, maxima/minima and intercepts from 0 - 360, you can work out these basic values for any value of x.
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    sin(-x)= -sin(x). Same goes for tan.
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    (Original post by Plagioclase)
    You need to know how the sin, cos and tan graphs look like. They're periodic so if you know the basic shape, maxima/minima and intercepts from 0 - 360, you can work out these basic values for any value of x.
    yes i do know
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    Use the fact that:

    sin(-x)=-sin(x)
    cos(-x)=cos(x)
    tan(-x) = sin(-x)/cos(-x) = -sin(x)/cos(x) = -tan(x).
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    (Original post by Radioactivedecay)
    sin(-x)= -sin(x). Same goes for tan.
    can you please explain ?
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    Tan and sin are odd functions so f(-x) = -f(x), then for sin you can use any of the 2 triangles (90,45,45 or 90,30,60) then just remember to add your minus back in
 
 
 
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Updated: February 23, 2018
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