Answer:
A = 119 units²
Step-by-step explanation:
side of square is (12√2)sin45 = 12
The portion of the diagonal that is NOT octagon is
12√2 - 12
There are four corner triangles. The sum of their areas is
(12√2 - 12)²
Area of the octagon is area of the square minus four corner triangle areas.
A = 12² - (12√2 - 12)²
A = 119.2935...
