
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
In $\Delta ABC$, $AC = BC$ and $m \angle DCB = 50^\circ$. Point $D$ is on extension of $BC$ such that $CD \parallel AB$, and point $E$ is on $AC$ such that $AE = EC$. Determine $m \angle ECD$.

[asy]
pair A,B,C,D,E;
B = dir(-50);
A = dir(-130);
D = (1.2, 0);
E = 0.5 * (A+C);
draw(C--B--A--cycle);
draw(A--E);
draw(C--D);
label("$A$", A, W);
label("$C$", C, NW);
label("$B$", B, E);
label("$D$", D, E);
label("$E$", E, N);
[/asy]

Present the answer in LaTex format: \boxed{Your answer}
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