16.4: Trigonometric Identities
- Page ID
- 106906
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- \(\sin^2 u + \cos^2 u = 1\)
- \(\tan u = \frac{\sin u}{\cos u}\)
- \(\sin \left( \frac{\pi}{2} − u \right) = \cos u\)
- \(\cos \left( \frac{\pi}{2} − u \right) = \sin u\)
- \(\sin (u \pm v) = \sin u \cos v \pm \cos u \sin v\)
- \(\cos (u \pm v) = \cos u \cos v \mp \sin u \sin v\)
- \(\sin (−u) = − \sin u\)
- \(\cos (−u) = \cos u\)
- \(\tan (−u) = − \tan u\)
- \(\sin u \cos v = \frac{1}{2} \left[ \sin (u + v) + \sin (u − v) \right]\)
- \(\sin u \sin v = \frac{1}{2} \left[ \cos (u − v) − \cos (u + v) \right]\)
- \(\cos u \cos v = \frac{1}{2} \left[ \cos (u − v) + \cos (u + v) \right]\)