the answer is the first one but i have no idea how to get that answer. can someone please explain i will be giving out brainliest answer

Answer:
The area will be:
[tex]A = 4345.6[/tex] square units
Step-by-step explanation:
Using the formula to calculate the area of regular octagon side
[tex]\:\:A\:=\:2\left(1+\sqrt{2}\right)s^2\:\:\:\:[/tex]
where 's' is the length of one side.
Given the length of one side = s = 30 inches
substituting s = 30 inches in the formula
[tex]\:A\:=\:2\left(1+\sqrt{2}\right)s^2\:\:\:\:[/tex]
[tex]=\:2\left(1+\sqrt{2}\right)\cdot \:\:30^2[/tex]
[tex]=2\cdot \:900\left(1+\sqrt{2}\right)[/tex]
[tex]A = 4345.6[/tex] square units
Therefore, the area will be:
[tex]A = 4345.6[/tex] square units