
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
The centers of two circles are $50$ inches apart. The smaller circle has a radius of $7$ inches and the larger one has a radius of $12$ inches.  
Find the length of the common internal tangent.
A) $\sqrt{2139}\text{ inches}$
B) $45\text{ inches}$
C) $40\text{ inches}$
D) $50\text{ inches}$
E) $47\text{ inches}$

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