Find the side $ a $ of an equilateral triangle if area $A = 129$.
Answer
$a = 17.2601$
Explanation
To find side $ a $ use formula:
$$ A = \dfrac{ \sqrt{ 3 } \cdot a^2 }{ 4 }$$After substituting $ A = 129 $ we have:
$$ 129 = \dfrac{ \sqrt{ 3 } \cdot a^2 }{ 4 }$$ $$ 129 \cdot 4 = \sqrt{ 3 } \cdot a^2 $$ $$ 516 = \sqrt{ 3 } \cdot a^2 $$ $$ a^2 = \dfrac{ 516 }{ \sqrt{ 3 } } $$ $$ a^2 = 172 \sqrt{ 3 } $$ $$ a = \sqrt{ 172 \sqrt{ 3 } } $$$$ a \approx 17.2601 $$This page was created using
Equilateral Triangle Calculator