∵AC=BC,∴∠CAB=∠CBA,
∵ΔBDC与ΔACE都是等边三角形,∴∠CAE=∠CBD=60°,
∴∠CAB-∠CAE=∠CBA-∠ABD,
即∠FAB=∠FBA,
∴FA=FB,
∴C、F都在线段AB的垂直平分线上,(用垂直平分线判定比全等快)。
∴CF平分AB,
即G为AB的中点。
1/2 ÷ 4/5 ÷ (2/9 × 3/8 )(5/6 - 3/4) ÷ 5/12 ÷ 9/53/7 ÷ [5/7 - (3/7 + 1/5)
1/2 ÷ 4/5 ÷ (2/9 × 3/8 )
=1/2 × 5/4 × 12
=15/2
(5/6 - 3/4) ÷ 5/12 ÷ 9/5
=1/12 × 12/5 × 5/9
=1/9
3/7 ÷ [5/7 - (3/7 + 1/5)]
=3/7 × 35/3
=5
四渡赤水调查