余弦定理应用：曲柄连杆机构动画

GeoGebra 命令及参数

1. Circle((0, 0), 1) → c
2. Polygon((1.24, 0.6), (5, 0.6), (5, -0.6), (1.24, -0.6)) → Cylinder, g, i, j, l
3. Segment(Pwheel, Pd) → L
4. Polygon((x(Pd), -0.6), (x(Pd), 0.6), (x(Pd) + 1.3, 0.6), (x(Pd) + 1.3, -0.6)) → Piston, a, b, e, f
5. Circle(O, 0.5) → h
6. Arc(h, (cos(rotation - π / 2), sin(rotation - π / 2)), (cos(rotation + π / 2), sin(rotation + π / 2))) → k
7. Segment(O, Pwheel) → Pseg1
8. Segment(O, Pd) → Pseg2
9. Segment(Po', Pd') → Tseg1
10. Segment(Pwheel', Pd') → Tseg3
11. Segment(Po', Pwheel') → Tseg2
12. Angle(Tseg1, Tseg2) → Θ