Question

2.2.5.9怎么算24

Answer 1

1: 2 × (5 - 2 + 9)
2: 2 × ((5 - 2) + 9)
3: 2 × (5 - (2 - 9))
4: 2 × (5 + 9 - 2)
5: 2 × ((5 + 9) - 2)
6: 2 × (5 + (9 - 2))
7: 2 × (9 - 2 + 5)
8: 2 × ((9 - 2) + 5)
9: 2 × (9 - (2 - 5))
10: 2 × (9 + 5 - 2)
11: 2 × ((9 + 5) - 2)
12: 2 × (9 + (5 - 2))
13: (5 - 2 + 9) × 2
14: ((5 - 2) + 9) × 2
15: (5 - (2 - 9)) × 2
16: (5 + 9 - 2) × 2
17: ((5 + 9) - 2) × 2
18: (5 + (9 - 2)) × 2
19: (9 - 2 + 5) × 2
20: ((9 - 2) + 5) × 2
21: (9 - (2 - 5)) × 2
22: (9 + 5 - 2) × 2
23: ((9 + 5) - 2) × 2
24: (9 + (5 - 2)) × 2
回答完毕，请采纳

Answer 2

设圆心角为θ，则sinθ/2=α/2R
这条弦所对的圆周角为圆心角的一半即θ/2，即θ/2=arcsin(α/2R)
弦长为α最小大于0，最大为直径：即0<α《2R

同弦所对圆周角互补：
所以还有一个圆周角：π-arcsin(α/2R)