STEP 1: find side $ a $
To find side $ a $ use formula:
$$ d = 2 \cdot a $$After substituting $ d = 51 $ we have:
$$ 51 = 2 \cdot a $$ $$ a = \dfrac{ 51 }{ 2 } $$ $$ a = \frac{ 51 }{ 2 } $$STEP 2: find area $ A $
To find area $ A $ use formula:
$$ A = \dfrac{ 3 \sqrt{ 3 } \cdot a^2 }{ 2 } $$After substituting $ a = \frac{ 51 }{ 2 } $ we have:
$$ A = \dfrac{ 3 \sqrt{ 3 } \cdot \left(\frac{ 51 }{ 2 }\right)^2 }{ 2 } $$ $$ A = \dfrac{ 3 \sqrt{ 3 } \cdot \frac{ 2601 }{ 4 } }{ 2 }$$ $$ A = \dfrac{ \frac{ 7803 \sqrt{ 3}}{ 4 } }{ 2 }$$ $$ A = \frac{ 7803 \sqrt{ 3}}{ 8 } $$