解:∵∠1=∠ACB,∴DE∥BC,∴∠2=∠DCF∵∠2=∠3,∴∠3=∠DCF,∴CD∥FG,∴∠BDC+∠DGF=180 °.
超级试练试题库
© 2017-2019 超级试练试题库,All Rights Reserved.