# Try folding a sheet

Geometry Level 3

A square sheet of paper $$ABCD$$ is so folded that $$B$$ falls on the midpoint of $$CD$$. If the crease divides $$BC$$ in the ratio $$\frac{a}{b}$$, where $$a$$ and $$b$$ are coprime positive integers, find $$a+b$$.

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