Answer:
[tex]\frac{1}{\sqrt{2} }[/tex] and - [tex]\frac{1}{\sqrt{2} }[/tex]
Step-by-step explanation:
Note that [tex]\frac{7\pi }{4}[/tex] is in the fourth quadrant where
cos > 0 and sin < 0
cos([tex]\frac{7\pi }{4}[/tex] ) = cos (2π - [tex]\frac{7\pi }{4}[/tex] ) = cos([tex]\frac{\pi }{4}[/tex] ) = [tex]\frac{1}{\sqrt{2} }[/tex]
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sin ([tex]\frac{7\pi }{4}[/tex] ) = - sin([tex]\frac{\pi }{4}[/tex] ) = - [tex]\frac{1}{\sqrt{2} }[/tex]
