the area of the square in the bottom, 11*11=121
find area of the triangles, (11*12.3)/2
11*12.3=135.3
135.3/2=67.65<--- area of the triangle
67.65*4=270.6
aka. just adding the areas of the triangles up
67.65+67.65+67.65+67.65=270.6
121+270.6=391.6
391.6 !