Answer:
DE=10
Explanation:
Given that in triangle ABC, $BC = 20 \sqrt{3}$ and $\angle C = 30^\circ$. Let the perpendicular bisector of $BC$ intersect $BC$ and $AC$ at $D$ and $E$,
To find length of DE
Please refer to the attachment for solution
Since perpendicular bisector we have DC = 1/2 BC = 10 sqrt 3
Using right triangle CDE, we get DE = 10