## mitchelsewbaran 2 years ago Find the exact value by using a half-angle identity.

1. mitchelsewbaran

2. dpaInc

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

3. dpaInc

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

4. dpaInc

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

5. mitchelsewbaran

i got 7pi/4

6. dpaInc

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. dpaInc

can you take it from here?