SOLUTION: 3 sin 2pi/3 - 4 cos 5pi/2. 5pi/2 isn't on unit circle, so what would I do?

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Question 415400: 3 sin 2pi/3 - 4 cos 5pi/2.
5pi/2 isn't on unit circle, so what would I do?
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
3%2Asin%282pi%2F3%29+-+4%2Acos%285pi%2F2%29

Yes 5pi%2F2 is on the unit circle, because you can make more 
than just one lap around the unit circle. One lap around the 
unit circle is considered to be an angle of 2pi.  So you 
subtract 2pi from %285pi%29%2F2, and that will be in the
same position on the unit circle, since it is exactly one lap
around the unit circle less.  So 

%285pi%29%2F2+-+2pi=%285pi%29%2F2-%284pi%29%2F2=pi%2F2

So %285pi%29%2F2 has the same trig functions as pi%2F2  

Therefore 

3%2Asin%282pi%2F3%29+-+4%2Acos%285pi%2F2%29

becomes

3%2Asin%282pi%2F3%29+-+4%2Acos%28pi%2F2%29

3%2A%28sqrt%283%29%2F2%29+-+4%2A0

%283sqrt%283%29%29%2F2+-+0

%283sqrt%283%29%29%2F2

Edwin