Question

初二数学求学霸帮忙！

Answer 1

连接AG
∵∠DAB=∠CAE
∴∠DAC=∠BAE
∵AD=AB ∠DAC=∠BAE AC=AE
∴⊿DAC≌⊿BAE
∴∠ADG=∠ABF DC=BE
∵DG=1/2DC BF=1/2BE
∴DG=BF
∵DA=BA ∠ADG=∠ABF DG=BF
∴⊿DAG≌⊿BAF
∴∠DAG=∠BAF
∴∠GAF=∠DAB
(1)∵∠DAB=60°
∴∠GAF=60°
∵AG=AF
∴∠AFG=(180°-∠GAF)/2=60°
(2)∵∠DAB=90°
∴∠GAF=90°
∵AG=AF
∴∠AFG=(180°-∠GAF)/2=45°
(3)∵∠DAB=α
∴∠GAF=α
∵AG=AF
∴∠AFG=(180°-∠GAF)/2=(180°-α)/2