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Mathematics 8 Online
OpenStudy (haleyelizabeth2017):

Find each value by referring to the graph of the sine or cosine function. cos(pi)

OpenStudy (anonymous):

have you been taught the unit circle?

OpenStudy (haleyelizabeth2017):

I have, but it's been a while..

OpenStudy (anonymous):

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jimthompson5910 (jim_thompson5910):

@haleyelizabeth2017 use the unit circle to find the angle pi then look at the x coordinate of the corresponding point x = cos(theta) y = sin(theta)

OpenStudy (haleyelizabeth2017):

Okay

OpenStudy (haleyelizabeth2017):

-1

OpenStudy (anonymous):

the points are ordered (cos,sin) so at pi, look at the ordered pair.

OpenStudy (haleyelizabeth2017):

Where would 3/2 pi be?

OpenStudy (haleyelizabeth2017):

270 degrees?

jimthompson5910 (jim_thompson5910):

yes 3pi/2 radians = 270 degrees this is the direction facing completely south

OpenStudy (haleyelizabeth2017):

Which sin (3/2pi)=-1 as well

jimthompson5910 (jim_thompson5910):

yep

OpenStudy (haleyelizabeth2017):

Where would -7/2pi be?

jimthompson5910 (jim_thompson5910):

add 2pi to that angle. What do you get?

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