Find the cosine of $ frac{2pi}{3} $ radians on the unit circle
Answer 1
Christopher Garcia
The angle $ \frac{2\pi}{3} $ radians is in the second quadrant.
In the second quadrant, the cosine of an angle is negative.
For $ \frac{2\pi}{3} $ radians, the reference angle is $ \frac{\pi}{3} $ radians.
Cosine of $ \frac{\pi}{3} $ radians is $ \frac{1}{2} $.
Therefore, the cosine of $ \frac{2\pi}{3} $ radians is:
$ \cos \left( \frac{2\pi}{3} \right) = -\frac{1}{2} $
Answer 2
Emily Hall
The angle $ frac{2pi}{3} $ radians is in the second quadrant where cosine values are negative.
The reference angle is $ frac{pi}{3} $ radians, whose cosine is $ frac{1}{2} $.
Thus, the cosine of $ frac{2pi}{3} $ radians is:
$ cos left( frac{2pi}{3}
ight) = -frac{1}{2} $
Answer 3
Olivia Lee
$ frac{2pi}{3} $ radians is in the second quadrant.
The reference angle is $ frac{pi}{3} $ radians with a cosine of $ frac{1}{2} $.
Hence, the cosine of $ frac{2pi}{3} $ radians is:
$ cos left( frac{2pi}{3}
ight) = -frac{1}{2} $
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