Determine the exact values of sine and cosine for an angle of 5π/6 in the unit circle
To determine the exact values of $\sin(\frac{5\pi}{6})$ and $\cos(\frac{5\pi}{6})$, we use the unit circle.
For the angle $\frac{5\pi}{6}$, it is in the second quadrant where sine is positive and cosine is negative. The reference angle for $\frac{5\pi}{6}$ is:
$$ \pi – \frac{5\pi}{6} = \frac{\pi}{6} $$
The values for sine and cosine at $\frac{\pi}{6}$ are known:
$$ \sin(\frac{\pi}{6}) = \frac{1}{2} $$
$$ \cos(\frac{\pi}{6}) = \frac{\sqrt{3}}{2} $$
Since $\frac{5\pi}{6}$ is in the second quadrant:
$$ \sin(\frac{5\pi}{6}) = \sin(\frac{\pi}{6}) = \frac{1}{2} $$
$$ \cos(\frac{5\pi}{6}) = – \cos(\frac{\pi}{6}) = – \frac{\sqrt{3}}{2} $$