STEP 1: find base area $ B $
To find base area $ B $ use formula:
$$ B = a^2 $$After substituting $ a = 4 $ we have:
$$ B = 4^2 $$ $$ B = 16 $$STEP 2: find lateral surface $ L $
To find lateral surface $ L $ use formula:
$$ L = 2 \cdot a \cdot s $$After substituting $ a = 4 $ and $ s = 5.4 $ we have:
$$ L = 8 \cdot 5.4 $$$$ L = 43.2 $$STEP 3: find total surface $ A $
To find total surface $ A $ use formula:
$$ A = B + L $$After substituting $ B = 16 $ and $ L = 43.2 $ we have:
$$ A = 16 + 43.2 $$ $$ A = 16 + 43.2 $$ $$ A = 59.2 $$