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Math Help - I don't really understand the unit circle that well...

  1. #1
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    I don't really understand the unit circle that well...

    ...and would love some help with various problems. I'll start with some of the simple ones from my homework and if people help me on those, i will ask more

    Using the unit circle, find each value.

    1. sin 90
    2. tan 360
    3. cot -180

    It's so confusing, I don't get it at all. This is how far i got for #1:

    Now, I thought that one part of that triangle will equal 1. but what part?

    thanks!!!!
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  2. #2
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    any point on the unit circle has coordinates (x,y) = (\cos{\theta}, \sin{\theta})

    so ... what are the coordinates at the top of the circle where \theta = 90^{\circ} ?
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  3. #3
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    (0, 1)?
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  4. #4
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    good! so, now you know \cos(90) = 0 and \sin(90) = 1.
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