3. In a regular triangular prism $A B C-A_{1} B_{1} C_{1}$, $D, E$ are points on the side edges $B B_{1}, C C_{1}$ respectively, $E C=B C=2 B D$, then the size of the dihedral angle formed by the section $A D E$ and the base $A B C$ is $\qquad$ .
Extend $ED$ to intersect the extension of $CB$ at point $F$, and connect $AF$. Since $BD \cong \frac{1}{2} CE \Rightarrow B$ is the midpoint of $CF$, and $AB = BC = FB$, thus $\angle CAF = 90^{\circ} \Rightarrow \angle CAE$ is the plane angle of the dihedral angle formed by the section $ADE$ and the base $ABC$. Therefore, the size of the dihedral angle formed by the section $ADE$ and the base $ABC$ is $45^{\circ}$.