The area of a regular octagon is equal eight times area of a triangle with the base 11 and the height 13.28:
[tex]A_8=8\cdot\dfrac{1}{2}\cdot11\cdot13.28=584.32[/tex]
The area of a square:
[tex]A_4=11^2=121[/tex]
The area of the shaded region:
[tex]A=A_6-A_4\to A=584.32-121=463.32\approx463[/tex]
Answer: D. 463 square units.
