check the picture below.
[tex] \bf 30\sqrt{2}=10h\implies \cfrac{30\sqrt{2}}{10}=h\implies \boxed{3\sqrt{2}=h}\\\\
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sin(\theta )=\cfrac{\stackrel{opposite}{3\sqrt{2}}}{\stackrel{hypotenuse}{6}}\implies sin(\theta )=\cfrac{\sqrt{2}}{2}
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\measuredangle \theta sin^{-1}\left( \cfrac{\sqrt{2}}{2} \right)\implies \measuredangle \theta =\cfrac{\pi }{4}\textit{or just }45^o [/tex]
