Answer:
4588 [in²].
Explanation:
1) the given octagon can be imagined as 8 triangles (see the attachment). In order to calculate the required area of the octagon, it is enough to calculate the area of one triangle then increase it 8 times:
2) area of one triangle is:
37*31/2 [in²].
3) the required area of the octagon is:
31*37*8/2=31*37*4=4588 [in²].