STEP 1: find angle $ \alpha $
To find angle $ \alpha $ use formula:
$$ \sin \left( \frac{ \alpha }{ 2 } \right) = \dfrac{ d_2 }{ d_1 } $$After substituting $ d_2 = 7 $ and $ d_1 = 14 $ we have:
$$ \sin \left( \frac{ \alpha }{ 2 } \right) = \dfrac{ 7 }{ 14 } $$ $$ \sin \left( \frac{ \alpha }{ 2 } \right) = \frac{ 1 }{ 2 } $$ $$ \frac{ \alpha }{ 2 } = \arcsin\left( \frac{ 1 }{ 2 } \right) $$ $$ \frac{ \alpha }{ 2 } = 30^o $$$$ \alpha = 30^o \cdot 2 $$$$ \alpha = 60^o $$STEP 2: find height $ h $
To find height $ h $ use formula:
$$ \sin \left( \frac{ \alpha }{ 2 } \right) = \dfrac{ h }{ d_1 } $$After substituting $ \alpha = 30 $ and $ d_1 = 14 $ we have:
$$ \sin \left( \frac{ 60^o }{ 2 } \right) = \dfrac{ h }{ 14 } $$ $$ \sin( 30 ) = \dfrac{ h }{ 14 } $$ $$ \frac{ 1 }{ 2 } = \dfrac{ h }{ 14 } $$$$ h = \frac{ 1 }{ 2 } \cdot 14 $$$$ h = 7 $$