\[\sin{22{^\circ}\ 30^{'}} = \sqrt{\frac{1 - \cos{45{^\circ}}}{2}} =\]
\[= \sqrt{\frac{1 - \frac{\sqrt{2}}{2}}{2}} = \sqrt{\frac{2 - \sqrt{2}}{4}} =\]
\[= \frac{\sqrt{2 - \sqrt{2}}}{4}\]