Question

数学问题,我不会,用初二的水平做

Answer 1

过C作CF垂直于AD延长线于F,因为AC平分∠BAD,∴CE=CF,AE=1/2(AB+AD),2AE=AB+AD,AE=EB+AD,又AE=AF,∴EB=FD,又∠CFA=∠CEB=90°,CE=CF,∴△CFD与△CEB全等,∠ABC=∠FDC,∠ABC+∠ADC=180°