
HalfAngle formulas
find the exact value of sin(5pi/12)
here's what I have, can you tell me if I'm doing it correctly and if I've simplified. I'm more than a little confused.
[sin(5pi/6)]/2 = +/ √[(1cosx)/2]
= +/ √{[1cos(5pi/6)]/2}
= +/ √ ({1[√(3)/2]}/2)
= +/ √ {[1+√(3)/2]/2}
And that's as far as I got. I'm not sure if I'm doing it correctly or if i am, i have no idea how to simplify further. :/
Thanks ahead of time, all help is very much appreciated.

Can't quite tell exactly what you're doing.
Here's a way...
$\displaystyle \sin(5\pi/12)=\sin(\pi/4 + \pi/6)$
= $\displaystyle \sin(\pi/4)\cos(\pi/6)+\cos(\pi/4)\sin(\pi/6)$
= $\displaystyle \frac{1}{\sqrt{2}}\frac{\sqrt{3}}{2} + \frac{1}{\sqrt{2}}\frac{1}{2}$
= $\displaystyle \frac{\sqrt{3}}{2\sqrt{2}} + \frac{1}{2\sqrt{2}}$
= $\displaystyle \frac{(1 + \sqrt{3})}{2\sqrt{2}}$
= $\displaystyle \frac{\sqrt{2}(1 + \sqrt{3})}{4}$