Wednesday, March 20, 2013
Half Angle Trig Identities
| \[ \begin{aligned} \sin \frac{u}{2} &= \pm \sqrt{ \frac{1 - \cos u}{2} } \\ \cos \frac{u}{2} &= \pm \sqrt{ \frac{1 + \cos u}{2} } \\ \tan \frac{u}{2} &= \pm \sqrt{ \frac{1 - \cos u}{1 + \cos u} } = \frac{\sin u}{1 + \cos u} = \frac{1 - \cos u}{\sin u} \\ \end{aligned} \] |
