Let $ABC$ be a triangle such that $|BC| = 7$ and $|AB| = 9$. If $m(\widehat{ABC}) = 2m(\widehat{BCA})$, then find the area of the triangle. The original answer is in the form of $m\sqrt{n}$, please give the value of m + n.

Let's think step by step and output the final answer within \boxed{}.
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