To find angle $ \alpha $ use formula:
$$ \sin \left( \alpha \right) = \dfrac{ h }{ a } $$After substituting $h = 72\, \text{cm}$ and $a = 23.5\, \text{cm}$ we have:
$$ \sin \left( \alpha \right) = \dfrac{ 72\, \text{cm} }{ 23.5\, \text{cm} } $$ $$ \sin \left( \alpha \right) = 3.0638 $$ $$ \alpha = \arcsin\left( 3.0638 \right) $$$ \arcsin(3.064) $ is not defined $ \Longrightarrow $ The problem has no solution.