
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 trapezoid $ABCD$, $CD$ is three times the length of $AB$. If the area of trapezoid $ABCD$ is $18$ square units, what is the area of $\triangle ABC?$

[asy]
draw((0,0)--(1,6)--(10,6)--(15,0)--cycle);
draw((10,6)--(0,0));
label("$C$",(0,0),W);
label("$A$",(1,6),NW);
label("$B$",(10,6),NE);
label("$D$",(15,0),E);
[/asy]

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