探索性命题一般多见于代数、三角和解析几何问题,其基本处理方法已逐渐成熟.但如果将探索性思想融合于立体几何问题中,其结果又会怎样呢?我们不妨先看2000年高考数学试题第19题:如图1,已知平行六面体ABCD～A1B1C1D1的底面ABCD是菱形,且∠C1CB=∠C1CD=∠BCD,(1)证明C1C⊥ Exploratory propositions are commonly found in algebraic, trigonometric, and analytical geometry problems. The basic processing methods have gradually matured. However, if the exploratory thinking is merged into the three-dimensional geometric problems, what will happen to the results? Let’s look at the 2000 college entrance mathematics Question 19: As shown in Figure 1, the bottom surface ABCD of the known parallelepiped ABCD-A1B1C1D1 is a rhombus, and ∠C1CB=∠C1CD=∠BCD, (1) Prove C1C⊥