STEP 1: find side $ a $
To find side $ a $ use formula:
After substituting $A = 8\, \text{cm}$ we have:
$$ A = a^2 $$ $$ a^2 = 8\, \text{cm} $$ $$ a = \sqrt{ 8\, \text{cm} } $$ $$ a = 2 \sqrt{ 2 } $$STEP 2: find circumradius $ R $
To find circumradius $ R $ use formula:
$$ R = \dfrac{ \sqrt{ 2 } \cdot a }{ 2 } $$After substituting $a = 2 \sqrt{ 2 }\, \text{cm}^0$ we have:
$$ R = \dfrac{ \sqrt{ 2 } \cdot 2 \sqrt{ 2 } }{ 2 } $$$$ R = \dfrac{ 4 }{ 2 } $$ $$ R = 2 $$