[tex]a = \frac{(9.5 + 23.1) \times 5.8}{2} \\ [/tex]
[tex]a = \frac{32.6 \times 5.8}{2} \\ [/tex]
[tex]a = 16.3 \times 5.8[/tex]
[tex]a = 94.54 \: \: {m}^{2} [/tex]