Hey guys, I need to find sin(3 $\displaystyle \pi $ /8)

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- Dec 5th 2009, 04:18 PMgoliath[SOLVED] Trig Identities (short problem)
Hey guys, I need to find sin(3 $\displaystyle \pi $ /8)

- Dec 5th 2009, 04:21 PMChris L T521
- Dec 5th 2009, 04:25 PMProve It
Alternatively, remember that $\displaystyle \sin{\left(\frac{\pi}{2} - \theta\right)} = \cos{\theta}$.

Can you see that $\displaystyle \frac{\pi}{2} - \frac{\pi}{8} = \frac{3\pi}{8}$?

So that would mean $\displaystyle \sin{\frac{3\pi}{8}} = \cos{\frac{\pi}{8}}$.

And you've been told what that is...