384 m²
Step-by-step explanation:
Since an octogon has 8 sides, it can be split into 8 different triangles.
To find the area of one triangle, use the formula a=bh½, or area=base×height×½. The base it 12m and the height is 8m, so do 8×12=96, then divide by 2 to get 48.
Since there are 8 triangles, multiply the area of 1 triangle by 8, and 48×8=384m².
Hope this helps!