Find the area $ A $ of a pyramid if side $a = 6$ and lateral edge $e = 5$.

$A = 84$

STEP 1: find base area $ B $

To find base area $ B $ use formula:

$$ B = a^2 $$

After substituting $ a = 6 $ we have:

$$ B = 6^2 $$ $$ B = 36 $$

STEP 2: find slant height $ s $

To find slant height $ s $ use Pythagorean Theorem:

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

After substituting $ a = 6 $ and $ e = 5 $ we have:

$$ s ^ {\,2} + \frac{ 6^2 }{ 4 } = 5^2 $$ $$ s ^ {\,2} + \frac{ 36 }{ 4 } = 5^2 $$ $$ s ^ {\,2} + 9 = 5^2 $$ $$ s ^ {\,2} = 25 - 9 $$ $$ s ^ {\,2} = 16 $$ $$ s = \sqrt{ 16 } $$$$ s = 4 $$

STEP 3: find lateral surface $ L $

To find lateral surface $ L $ use formula:

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

After substituting $ a = 6 $ and $ s = 4 $ we have:

$$ L = 12 \cdot 4 $$$$ L = 48 $$

STEP 4: find total surface $ A $

To find total surface $ A $ use formula:

$$ A = B + L $$

After substituting $ B = 36 $ and $ L = 48 $ we have:

$$ A = 36 + 48 $$ $$ A = 36 + 48 $$ $$ A = 84 $$

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