To find area $ A $ use formula:
$$ A = \dfrac{ a \cdot a \cdot \sin( \alpha ) }{ 1 } $$After substituting $ a = 6 $ , $ a = 6 $ and $ \alpha = 60^o $ we have:
$$ A = \dfrac{ 6 \cdot 6 \cdot \sin( 60^o ) }{ 1 } $$ $$ A = \dfrac{ 6 \cdot 6 \cdot \frac{\sqrt{ 3 }}{ 2 } }{ 1 } $$ $$ A = \dfrac{ 36 \cdot \frac{\sqrt{ 3 }}{ 2 } }{ 1 } $$ $$ A = \dfrac{ 18 \sqrt{ 3 } }{ 1 } $$ $$ A = 18 \sqrt{ 3 } $$