Answer: 40K
Step-by-step explanation:
We know that the area of a regular polygon is given by :-
[tex]A=\frac{1}{2}*Apothem*Perimeter[/tex]
Given: The side of regular octagon = 10
Then, the perimeter of the regular octagon =[tex]8(side)=8(10)=80[/tex]
Now, the area of given regular octagon is given by :-
[tex]A=\frac{1}{2}\timesK\times80\\\Rightarrow\ A=40K[/tex]