Question

如图,在三角形abc中,∠abc=2∠acb,ad⊥bc于d,e是bc的中点,证明AB=2DE

Answer 1

取AB中点为F,连结DF,EF因为F为RT△ABD斜边AB中点,所以DF=AF=BF,所以∠ABC=∠BDF因为E为BC中点,所以EF//AC,所以∠ACB=∠BEF因为∠BDF=∠BEF+∠DFE所以∠ABC=∠BDF=∠BEF+∠DFE==∠ACB+∠DFE因为∠ABC=2∠ACB所以∠ACB...