The greatest common factor of the two terms is 33a^3.
With the numbers 66 and 99, the greatest common factor is 33. It is the largest number that divides evenly into both.
For the variables, the most that is in common in both is a^3.
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Explanation:</h2><h2>
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The diagram is missing but I'll assume that the arc BDC is:

And another arc, let's call it FGH. measures:

If those arc are equal, then this equation is true:

Substituting k into the first equation:
