STEP 1: find side $ a $
To find side $ a $ use formula:
$$ s = \sqrt{ 3 } \cdot a $$After substituting $ s = 20 $ we have:
$$ 20 = \sqrt{ 3 } \cdot a $$ $$ a = \dfrac{ 20 }{ \sqrt{ 3 } } $$ $$ a = \frac{ 20 \sqrt{ 3}}{ 3 } $$STEP 2: find diagonal $ d $
To find diagonal $ d $ use formula:
$$ d = 2 \cdot a $$After substituting $ a = \frac{ 20 \sqrt{ 3}}{ 3 } $ we have:
$$ d = 2 \cdot \frac{ 20 \sqrt{ 3}}{ 3 } $$ $$ d = \frac{ 40 \sqrt{ 3}}{ 3 } $$