STEP 1: find angle $ \alpha $
To find angle $ \alpha $ use formula:
$$ \sin \left( \alpha \right) = \dfrac{ h }{ a } $$After substituting $ h = 39 $ and $ a = 57 $ we have:
$$ \sin \left( \alpha \right) = \dfrac{ 39 }{ 57 } $$ $$ \sin \left( \alpha \right) = \frac{ 13 }{ 19 } $$ $$ \alpha = \arcsin\left( \frac{ 13 }{ 19 } \right) $$ $$ \alpha = 43.1736^o $$STEP 2: find angle $ \beta $
To find angle $ \beta $ use formula:
$$ \alpha + \beta = 90^o $$After substituting $ \alpha = 43.1736^o $ we have:
$$ 43.1736^o + \beta = 90^o $$ $$ \beta = 90^o - 43.1736^o $$ $$ \beta = 46.8264^o $$