Question: In triangle ABC, the angle bisector of angle A divides side BC into segments BD = x and CD = 2x+3. If AB = 12 and AC = 18, find the value of x.
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Question: In circle $O$, chord $AB$ is perpendicular to diameter $CD$. If $AC=12$ and $BD=6$, find the length of $AB$.
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What is the condition for two triangles to be congruent, involving side lengths, angle measures, and corresponding sides/angles?