To find area $ A $ use formula:
$$ A = \dfrac{ 3 \sqrt{ 3 } \cdot a^2 }{ 2 } $$After substituting $ a = \frac{ 713 }{ 100 } $ we have:
$$ A = \dfrac{ 3 \sqrt{ 3 } \cdot \left(\frac{ 713 }{ 100 }\right)^2 }{ 2 } $$ $$ A = \dfrac{ 3 \sqrt{ 3 } \cdot \frac{ 508369 }{ 10000 } }{ 2 }$$ $$ A = \dfrac{ \frac{ 1525107 \sqrt{ 3}}{ 10000 } }{ 2 }$$ $$ A = \frac{ 1525107 \sqrt{ 3}}{ 20000 } $$