STEP 1: find angle $ \beta $
To find angle $ \beta $ use formula:
$$ \sin \left( \frac{ \beta }{ 2 } \right) = \dfrac{ h }{ d_2 } $$After substituting $ h = 12 $ and $ d_2 = 13 $ we have:
$$ \sin \left( \frac{ \beta }{ 2 } \right) = \dfrac{ 12 }{ 13 } $$ $$ \sin \left( \frac{ \beta }{ 2 } \right) = \frac{ 12 }{ 13 } $$ $$ \frac{ \beta }{ 2 } = \arcsin\left( \frac{ 12 }{ 13 } \right) $$ $$ \frac{ \beta }{ 2 } = 67.3801^o $$$$ \beta = 67.3801^o \cdot 2 $$$$ \beta = 134.7603^o $$STEP 2: find angle $ \alpha $
To find angle $ \alpha $ use formula:
$$ \alpha + \beta = 90^o $$After substituting $ \beta = 134.7603^o $ we have:
$$ \alpha + 134.7603^o = 90^o $$ $$ \alpha = 90^o - 134.7603^o $$ $$ \alpha = -44.7603^o $$The result has to be greater than zero. $ \Longrightarrow $ The problem has no solution.