To find side $ b $ use Pythagorean Theorem:

$$ a^2 + b^2 = d^2 $$

After substituting $a = 9\, \text{cm}$ and $d = 292.5\, \text{cm}$ we have:

$$ \left( 9\, \text{cm} \right)^{2} + b^2 = \left( 292.5\, \text{cm} \right)^{2} $$ $$ b^2 = \left( 292.5\, \text{cm} \right)^{2} - \left( 9\, \text{cm} \right)^{2} $$ $$ b^2 = 85556.25\, \text{cm}^2 - 81\, \text{cm}^2 $$ $$ b^2 = 85475.25\, \text{cm}^2 $$ $$ b = \sqrt{ 85475.25\, \text{cm}^2 } $$$$ b = 292.3615\, \text{cm} $$

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