To find height $ h $ use formula:
$$ A = a \cdot h $$After substituting $A = 216\, \text{cm}$ and $a = 19\, \text{cm}$ we have:
$$ 216\, \text{cm} = 19\, \text{cm} \cdot h $$$$ h = \dfrac{ 216\, \text{cm} }{ 19\, \text{cm} } $$$$ h = \frac{ 216 }{ 19 } $$