四面体体积的下和近似（卡瓦列里原理）

GeoGebra 命令及参数

1. Sequence(A + (k / n * (T - A)), k, 1, n - 1) → A_{up}
2. Sequence(B + (k / n * (T - B)), k, 1, n - 1) → B_{up}
3. Sequence(C + (k / n * (T - C)), k, 1, n - 1) → C_{up}
4. Sequence(Element[A_{up}, k] - (0, 0, h_{n}), k, 1, n - 1) → A_{down}
5. Sequence(Element[B_{up}, k] - (0, 0, h_{n}), k, 1, n - 1) → B_{down}
6. Sequence(Element[C_{up}, k] - (0, 0, h_{n}), k, 1, n - 1) → C_{down}
7. Sequence(Prism[Element[A_{down}, k], Element[B_{down}, k], Element[C_{down}, k], Element[A_{up}, k]], k, 1, n - 1) → Prisms
8. Segment(A, T) → a
9. Segment(B, T) → b
10. Segment(C, T) → c
11. Segment(B, C) → d
12. Segment(C, A) → e
13. Segment(A, B) → f
14. Segment(P, T) → height
15. Length(height) → h