| ${0}^{0}$ | ${30}^{0}$ | ${45}^{0}$ | ${60}^{0}$ | ${90}^{0}$ | ${15}^{0}$ | ${75}^{0}$ | |
|---|---|---|---|---|---|---|---|
| Sin | 0 | $\frac{1}{2}$ | $\frac{{\sqrt{2}}}{2}$ | $\frac{{\sqrt{3}}}{2}$ | 1 | $\frac{{\sqrt{6}}-{\sqrt{2}}}{4}$ | $\frac{{\sqrt{6}}+{\sqrt{2}}}{4}$ |
| Cos | 1 | $\frac{{\sqrt{3}}}{2}$ | $\frac{{\sqrt{2}}}{2}$ | $\frac{1}{2}$ | 0 | $\frac{{\sqrt{6}}+{\sqrt{2}}}{4}$ | $\frac{{\sqrt{6}}-{\sqrt{2}}}{4}$ |
| Tan | 0 | $\frac{{\sqrt{3}}}{3}$ | 1 | $\sqrt{3}$ | 不存在 | 不用记 | 不用记 |
\sum_{x=0}^n f(x)
$\sqrt{x}$
$e^{\imath x} = \cos{x} + \imath\sin{x}$.
SE = \frac{\sigma}{\sqrt{n}}