Contact us
Choose a category below so we can get back to you as quickly as possible.
證明:∵AD∥BC,∴∠A+∠ABC=180°,∠C+∠ADC=180°,∵∠A=∠C,∴∠ABC=∠ADC,∵BE、DF分別平分∠ABC和∠CDA,∴∠EBC=12∠ABC,∠EDF=12∠ADC,∴∠EBC=∠EDF,∵AD∥BC,∴∠DFC=∠EDF,∴∠EBC=∠DFC,∴BE∥DF.
We and our partners use cookies and other technologies to analyze traffic and optimize your experience. View more info and control your cookies settings at any time in our Cookies Policy.