Answer:
[tex]403 + 40\sqrt{3}~~ ft^2[/tex]
Step-by-step explanation:
[tex](20+\sqrt{3})(20+\sqrt{3}) = 20^2 + 2\cdot 20 \cdot \sqrt{3} + \sqrt{3}^2 = 400 + 40\sqrt{3} + 3 = 403 + 40\sqrt{3}[/tex]