STEP 1: find base area $ B $
To find base area $ B $ use formula:
$$ B = a^2 $$After substituting $ a = 15.5 $ we have:
$$ B = 15.5^2 $$ $$ B = 240.25 $$STEP 2: find lateral surface $ L $
To find lateral surface $ L $ use formula:
$$ L = 2 \cdot a \cdot s $$After substituting $ a = 15.5 $ and $ s = 19.3 $ we have:
$$ L = 31 \cdot 19.3 $$$$ L = 598.3 $$STEP 3: find total surface $ A $
To find total surface $ A $ use formula:
$$ A = B + L $$After substituting $ B = 240.25 $ and $ L = 598.3 $ we have:
$$ A = 240.25 + 598.3 $$ $$ A = 240.25 + 598.3 $$ $$ A = 838.55 $$