Question 20
In triangle $ABC$, $\angle C=120^\circ$ and $BC=2AC$. $D$ is the midpoint of $BC$, and $E$ is on side $AB$ such that $ED\perp BC$. If $BE=20$, find $AE$.
Answer format: an integer without units. Leading zeros are optional; the source uses four digit boxes.
Answer format: an integer without units. Leading zeros are optional; the source uses four digit boxes.