Question 857580
Without using a calculator determine if each function is poositive or negative
a) sin 145 degrees
b) cos 160 degrees
c) cos 210 degrees
d) sin 255 degrees
e) cos 355 degrees 
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Check the quadrants.
a) sin 145 degrees Q2 --> +
b) cos 160 degrees Q2 --> -
c) cos 210 degrees Q3 --> -
d) sin 255 degrees Q3 --> -
e) cos 355 degrees Q4 --> +
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Do you know how that works?  You don't need to memorize it.