Considering the perimeter (P)
[tex]p = 2 \times b + 2 \times h[/tex]
where b is the base and h is the height, then
[tex]12 = 2 \times 4 \times 2 \times h \\ \\ h = \frac{12 - (2 \times 4)}{2} \\ \\ h = 2[/tex]
Being the area (A)
[tex]a = b \times h \\ \\ a = 4 \times 2 \\ \\ a = 8 {m}^{2} [/tex]
