We have to find the surface area of the cylinder.
The radius is 7 ft and the height is 21 ft.
We can write this as:
[tex]\begin{gathered} A=2\cdot A_b+A_f \\ A=2\cdot\pi r^2+2\pi rh \\ A=2\cdot3.14\cdot7^2+2\cdot3.14\cdot7\cdot21 \\ A=2\cdot3.14\cdot49+2\cdot3.14\cdot7\cdot21 \\ A=307.72+923.16 \\ A=1230.88\text{ ft}^2 \end{gathered}[/tex]
Answer: the surface of the cylinder is 1230.88 square feet.
