题干
观察下列等式：
=1﹣
，
=
﹣
，
=
﹣
，
| 1 |
| 1 |
| × |
| 2 |
| 1 |
| 2 |
| 1 |
| 2 |
| × |
| 3 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| × |
| 4 |
| 1 |
| 3 |
| 1 |
| 4 |
把以上三个等式两边分别相加得：
+
+
=1﹣
+
﹣
+
﹣
=1﹣
=
．
| 1 |
| 1 |
| × |
| 2 |
| 1 |
| 2 |
| × |
| 3 |
| 1 |
| 3 |
| × |
| 4 |
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 4 |
| 3 |
| 4 |
的相似比为2：3，△ 
的相似比为3：5，那么△