Question 306787: Find sec(2/3pi).
Answer by texttutoring(324)   (Show Source):
You can put this solution on YOUR website! Draw the unit circle.
2pi/3 radians is equivalent to 120 degrees.
This means that your terminal arm will create an angle of 60 degrees with the x axis, in the second quadrant.
Secant = 1/Cosine
The value of Cos(120) can then be found from the 30-60-90 triangle drawn in the second quadrant, as 120 degrees has a reference angle of 60 degrees. (This would probably make more sense with a picture, but I don't know how to draw one on here.)
Cos(120)=-1/2
Sec(120) = -2/1 = -2
Let me know if you need any clarifications.
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