Answer:
[tex]-\frac{\sqrt{2} }{2}[/tex]
Step-by-step explanation:
Trig unit circle shows -->
[tex]\text{sin}({\frac{5\pi }{4 })=-\text{sin}(\frac{\pi }{4} )[/tex]
Trig Table of Special Arcs gives --> [tex]\text{sin}(\frac{\pi }{4} )=\frac{\sqrt{2} }{2}[/tex], therefore:
[tex]sin(\frac{5\pi }{4} )=-\frac{\sqrt{2} }{2}[/tex]