[tex] \huge \boxed { \sf Answer}[/tex]
[tex] \cos(21°) = \frac{9}{y} \\ = > 0.9336 = \frac{9}{y} \\ = > \frac{y}{9} = 0.9 336\\ = > y = 9 \times 0.9336 \\ = > y = 8.4024 \\ = > y = 8.4[/tex]
Hope you could understand.
If you have any query, feel free to ask.
