SOLUTION: Give the exact value of the following. If it is undefined, so state. 1)tan 4pi/3 2)sin 120 degrees 3)cos 5pi/6 I am having trouble figuring out all of the problems like the

Question 212525: Give the exact value of the following. If it is undefined, so state.
1)tan 4pi/3
2)sin 120 degrees
3)cos 5pi/6
I am having trouble figuring out all of the problems like the ones listed. Please help.

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Give the exact value of the following. If it is undefined, so state.
1)tan 4pi/3
---
(4/3)pi is 60 degrees in the 3rd quadrant
tan[(4/3)pi] = -sqrt(3)
--------------------------------
2)sin 120 degrees
120 has a reference angle of 60 degrees in the 2nd quadrant
sin(120) = sqrt(3)
--------------------------------
3)cos 5pi/6
(5/6)pi has a reference angle of 30 degrees in the 2nd quadrant:
cos[(5/6)pi] = -cos(30) = -sqrt(3)/2
=====================================
Cheers,
Stan H.
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