To find area $ A $ use formula:
$$ A = \dfrac{ 3 \sqrt{ 3 } \cdot a^2 }{ 2 } $$After substituting $ a = 6 \sqrt{ 3 } $ we have:
$$ A = \dfrac{ 3 \sqrt{ 3 } \cdot \left(6 \sqrt{ 3 }\right)^2 }{ 2 } $$ $$ A = \dfrac{ 3 \sqrt{ 3 } \cdot 108 }{ 2 }$$ $$ A = \dfrac{ 324 \sqrt{ 3 } }{ 2 }$$ $$ A = 162 \sqrt{ 3 } $$