(1)角ADE=角AED=角CDE+角C,角ADC=角ADE+角角CDE=2角CDE+角C,角B+角BAD=角ADC=2角CDE+角C,即角BAD=2角CDE
(2)成立 角BAD+角ADC=角ACD=角CDE+角ADC+角CDE,即角BAD=2角CDE
(1)角ADE=角AED=角CDE+角C,角ADC=角ADE+角角CDE=2角CDE+角C,角B+角BAD=角ADC=2角CDE+角C,即角BAD=2角CDE
(2)成立 角BAD+角ADC=角ACD=角CDE+角ADC+角CDE,即角BAD=2角CDE