To find side $ l $ use Pythagorean Theorem:
$$ r^2 + h^2 = l^2 $$After substituting $r = 10\, \text{cm}$ and $h = 942\, \text{cm}$ we have:
$$ \left( 10\, \text{cm} \right)^{2} + \left( 942\, \text{cm} \right)^{2} = l^2 $$ $$ 100\, \text{cm}^2 + 887364\, \text{cm}^2 = l^2 $$ $$ l^2 = 887464\, \text{cm}^2 $$ $$ l = \sqrt{ 887464\, \text{cm}^2 } $$$$ l = 2 \sqrt{ 221866 }\, \text{cm} $$