讲解这道题---**Textual Information:** 1. 如图, $\text{□ABCD}$ 中, $\text{AB}=9\text{cm}$, 对角线 $\text{AC}$、$\text{BD}$ 相交于点 $\text{O}$, 若 $\triangle \text{COD}$ 的周长为 $20\text{cm}$, 且 $\text{AC}$ 比 $\text{BD}$ 长 $6\text{cm}$, 试求对角线 $\text{AC}$、$\text{BD}$ 的长. **Chart/Diagram Description:** * **Type:** Geometric figure (parallelogram with diagonals). * **Main Elements:** * **Shape:** Parallelogram $\text{ABCD}$. * **Points:** Vertices labeled A, B, C, D. Intersection point of diagonals labeled O. * **Lines:** Sides of the parallelogram $\text{AB}$, $\text{BC}$, $\text{CD}$, $\text{DA}$. Diagonals $\text{AC}$ and $\text{BD}$. * **Relationship:** Diagonals $\text{AC}$ and $\text{BD}$ intersect at point $\text{O}$. The figure shows a typical parallelogram where the diagonals bisect each other. Points A, B, C, D are arranged in a counter-clockwise order.