Question 1203403
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Here's a diagram of the unit circle
<img width=400 src = "https://etc.usf.edu/clipart/43200/43216/unit-circle8_43216_lg.gif">
Image Source:
<a href="https://etc.usf.edu/clipart/43200/43216/unit-circle8_43216.htm">https://etc.usf.edu/clipart/43200/43216/unit-circle8_43216.htm</a>
This diagram is used a lot in trigonometry. So be sure to have a copy somewhere in your notes. 


The angle 3pi/2 is pointing directly south toward 270 degrees.
The associated point on the unit circle is (0,-1)
x = 0
y = -1
The y value is result of sin(3pi/2) because 
x = cos(theta)
y = sin(theta)


Therefore, <font color=red>sin(3pi/2) = -1</font>


A calculator can be used to compute this. Make sure the calculator is in radian mode.
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