\( \dfrac{b}{sin \; \beta}=\dfrac{c}{sin \; \gamma} \)
\( \dfrac{10\sqrt{3}}{sin \; 60^0}=\dfrac{c}{sin \; 30^0} \)
\( \dfrac{10\sqrt{3}}{ \left (\dfrac{\sqrt{3}}{2} \right ) }=\dfrac{c}{0,5} \)
\( 10\sqrt{3}: \dfrac{\sqrt{3}}{2}= \dfrac{c}{0,5} \)
\( 10\sqrt{3} \cdot \dfrac{2}{\sqrt{3}}= \dfrac{c}{0,5} \)
\( 20= \dfrac{c}{0,5} \)
\( c=10 \)
Ответ: \( c=10 \)