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Mathematics 7 Online
OpenStudy (anonymous):

Use the unit circle to find cos(-90o).

OpenStudy (phi):

can you show the angle -90 degrees ?

OpenStudy (anonymous):

What do you mean? Is it undefined?

OpenStudy (anonymous):

@phi

OpenStudy (phi):

no, it's defined. but the first step to this problem is drawing an x-axis and y-axis, and put in -90 degrees

OpenStudy (phi):

you measure an angle from the x-axis (positive direction) negative angles means move clockwise (i.e. down) move 90 degees

OpenStudy (anonymous):

On the unit circle?

OpenStudy (anonymous):

Wait so is it (-1,0) @phi

OpenStudy (anonymous):

Wait no (1,0)

OpenStudy (phi):

|dw:1425328022219:dw|

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