AP Precalculus / Unit 3: Trigonometric and Polar Functions
3.3 Sine and Cosine Function Values
Notes
Know the special angles:
| $\theta$ | $0$ | $\frac{\pi}{6}$ | $\frac{\pi}{4}$ | $\frac{\pi}{3}$ | $\frac{\pi}{2}$ |
|---|---|---|---|---|---|
| $\sin$ | $0$ | $\displaystyle \frac{1}{2}$ | $\displaystyle \frac{\sqrt2}{2}$ | $\displaystyle \frac{\sqrt3}{2}$ | $1$ |
| $\cos$ | $1$ | $\displaystyle \frac{\sqrt3}{2}$ | $\displaystyle \frac{\sqrt2}{2}$ | $\displaystyle \frac{1}{2}$ | $0$ |
- Use reference angles and quadrant signs for other angles.
Practice
$\displaystyle \cos\frac{\pi}{3}=$
From the table.
$\displaystyle \sin\frac{5\pi}{6}=$
Reference angle $\displaystyle \frac{\pi}{6}$ in quadrant II, where sine is positive.
$\cos\pi=$
The point $(-1,0)$.
Ready for more? Take the Unit 3 test.