Find the area $ A $ of a pyramid if side $a = 12$ and height $h = 8$.

$A = 384$

STEP 1: find base area $ B $

To find base area $ B $ use formula:

$$ B = a^2 $$

After substituting $ a = 12 $ we have:

$$ B = 12^2 $$ $$ B = 144 $$

STEP 2: find slant height $ s $

To find slant height $ s $ use Pythagorean Theorem:

$$ h^2 + \frac{ a^2 }{ 4 } = s^2 $$

After substituting $ h = 8 $ and $ a = 12 $ we have:

$$ 8^2 + \frac{ 12^2 }{ 4 }= s^2 $$ $$ 64 + \frac{ 144 }{ 4 }= s^2 $$ $$ 64 + 36 = s^2 $$ $$ s^2 = 100 $$ $$ s = \sqrt{ 100 } $$$$ s = 10 $$

STEP 3: find lateral surface $ L $

To find lateral surface $ L $ use formula:

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

After substituting $ a = 12 $ and $ s = 10 $ we have:

$$ L = 24 \cdot 10 $$$$ L = 240 $$

STEP 4: find total surface $ A $

To find total surface $ A $ use formula:

$$ A = B + L $$

After substituting $ B = 144 $ and $ L = 240 $ we have:

$$ A = 144 + 240 $$ $$ A = 144 + 240 $$ $$ A = 384 $$

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