Step-by-step explanation:
[tex] \sin \: 225 \degree \: \\ = \sin \: (180 \degree + 45\degree) \\ = - \sin \: 45 \degree \\ = - \frac{1}{ \sqrt{2} } \\ = - \frac{\sqrt{2}}{2}\\
= - \frac{1.4142}{2}\\=-0.7071
\\ \red{ \boxed{\therefore \: \sin \: 225 \degree = - 0.7071}}[/tex]