STEP 1: find side $ a $

To find side $ a $ use formula:

After substituting $B = 64\, \text{cm}$ we have:

$$ B = a^2 $$ $$ a^2 = 64\, \text{cm} $$ $$ a = \sqrt{ 64\, \text{cm} } $$ $$ a = 8 $$

STEP 2: find lateral surface $ L $

To find lateral surface $ L $ use formula:

$$ L = 2 \cdot a \cdot s $$

After substituting $a = 8\, \text{cm}^0$ and $s = 15.3\, \text{cm}$ we have:

$$ L = 16 \cdot 15.3\, \text{cm} $$$$ L = 244.8\, \text{cm} $$

STEP 3: find total surface $ A $

To find total surface $ A $ use formula:

$$ A = B + L $$

After substituting $B = 64\, \text{cm}$ and $L = 244.8\, \text{cm}$ we have:

$$ A = 64\, \text{cm} + 244.8\, \text{cm} $$ $$ A = 64\, \text{cm} + 244.8\, \text{cm} $$ $$ A = 308.8\, \text{cm} $$

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