STEP 1: find side $ a $
To find side $ a $ use formula:
$$ h = \dfrac{ \sqrt{ 3 } \cdot a }{ 2 } $$After substituting $h = 2\, \text{cm}$ we have:
$$ 2\, \text{cm} = \dfrac{ \sqrt{ 3 } \cdot a }{ 2 } $$ $$ \sqrt{ 3 } \cdot a = 2\, \text{cm} \cdot 2 $$ $$ \sqrt{ 3 } \cdot a = 4\, \text{cm} $$ $$ a = \dfrac{ 4\, \text{cm} }{ \sqrt{ 3 } } $$ $$ a = \frac{ 4 \sqrt{ 3}}{ 3 }\, \text{cm} $$STEP 2: find area $ A $
To find area $ A $ use formula:
$$ A = \frac{ a^2 \sqrt{3}}{2} + 3 a l $$After substituting $a = \dfrac{ 4 \sqrt{ 3}}{ 3 }\, \text{cm}$ and $l = 4\, \text{cm}$ we have:
$$ A = \frac{ \frac{ 4 \sqrt{ 3}}{ 3 }\, \text{cm}^2 \sqrt{3}}{2} + 3 \cdot \frac{ 4 \sqrt{ 3}}{ 3 }\, \text{cm} \cdot 4\, \text{cm} $$$$ A = \frac{ \frac{ 16 }{ 3 }\, \text{cm}^2 \sqrt{3}}{2} + 3 \cdot \frac{ 16 \sqrt{ 3}}{ 3 }\, \text{cm}^2 $$$$ A = \frac{ \frac{ 16 \sqrt{ 3}}{ 3 }\, \text{cm}^2}{2} + 16 \sqrt{ 3 }\, \text{cm}^2 $$$$ A = \frac{ 8 \sqrt{ 3}}{ 3 }\, \text{cm}^2 + 16 \sqrt{ 3 }\, \text{cm}^2 $$$$ A = \frac{ 56 \sqrt{ 3}}{ 3 }\, \text{cm}^2 $$