Answer:
[tex]A=128\ cm^2[/tex]
Step-by-step explanation:
we know that
The area of the polygon is equal to the area of a square plus the area of four congruent triangles
so
[tex]A=b^2+4[\frac{1}{2}(b)(h)][/tex]
where
[tex]b=8\ cm\\h=4\ cm[/tex]
substitute
[tex]A=8^2+4[\frac{1}{2}(8)(4)][/tex]
[tex]A=64+64=128\ cm^2[/tex]
