## anonymous 3 years ago Find the exact value by using a half-angle identity.

1. anonymous

2. anonymous

HINT: $$\large sin(x/2)=\pm \sqrt{\frac{1-cosx}{2}}$$

3. anonymous

can you figure out what x = ??? first?

4. anonymous

find x: $$\large \frac{7\pi}{8}=\frac{x}{2}$$

5. anonymous

i got 7pi/4

6. anonymous

ok... so plugging that into the half angle formula: $$\large sin(\frac{7\pi}{8})=sin(\frac{\frac{7\pi}{4}}{2})=\pm \sqrt{\frac{1-cos(\frac{7\pi}{4})}{2}}$$

7. anonymous

can you take it from here?