To find side $ a $ use formula:
$$ A = 6 \cdot a^2 $$After substituting $A = 4998\, \text{cm}$ we have:
$$ 4998\, \text{cm} = 6 \cdot a^2 $$ $$ a^2 = \dfrac{ 4998\, \text{cm} }{ 6 } $$ $$ a^2 = 833\, \text{cm} $$ $$ a = \sqrt{ 833\, \text{cm} } $$ $$ a = 7 \sqrt{ 17 } $$