## Algebra 2 (1st Edition)

$\dfrac{\sqrt {2-\sqrt 2}}{2}$
Write the correct identity such as: $\sin (a/2)=\sqrt {\dfrac{1-\cos a}{2}}$ Plug the data into the above equation. $\sqrt {\dfrac{1-\cos (45)}{2}}=\sqrt {\dfrac{1-(\sqrt 2/2)}{2}}$ or, $=\sqrt {\dfrac{2-\sqrt 2}{4}}$ or, $=\dfrac{\sqrt {2-\sqrt 2}}{2}$