As shown in the figure, in the cube abcd-a1, B1, C1, D1 (1) Write the edges with point B as the endpoint respectively; (2) If an ant wants to climb from point a to vertex B, how can it get the shortest route? Why? (3) What if point a crawls along the surface to point C1?

As shown in the figure, in the cube abcd-a1, B1, C1, D1 (1) Write the edges with point B as the endpoint respectively; (2) If an ant wants to climb from point a to vertex B, how can it get the shortest route? Why? (3) What if point a crawls along the surface to point C1?

(1)BA,BC,BB1
(2) Climb along AB, because the line between two points is the shortest
(3) A → midpoint of CD → C1

It is known that square abcd-a1b1c1d1, O is the intersection of diagonal lines of ABCD on the bottom
Verification 1. Ab1d1 of C1O ‖ plane
2. A1C ⊥ surface ab1d1

Ab1 ∥ DC1, AD1 ∥ BC1 ∥ ab1d1 ∥ bdc1. OC1 ∈ bdc1. C1O ∥ ab1d1
2. Let p be the center of abb1a1 ⊥ CB ⊥ abb1a1 ⊥ Ab1 ⊥ BC and Ab1 ⊥ A1B ⊥ Ab1 ⊥ plane A1 BC.AB1 ⊥A1C
Similarly, b1d1 ⊥ a1c1c. B1d1 ⊥ A1C. A1C ⊥ ab1d1