Cho \(\Delta ABCvuongtaiA.Tiaphangiaccua\widehat{B}catACtaiE.TuEkeEHvuonggocBCtaiH.\)
\(a>CMR:\Delta ABE=\Delta HBE\)
\(b>CMR:BEladuongtrungtruccuaAH\)
\(c>GoigiaodiemcuaABvaEHlaK.Xacdinhdangcua\Delta ECK\)
\(d>.CMR:AHsongsongCK\)
\(e>Timdieukiencua\Delta ABCde\widehat{AEB}=\widehat{HEC}\)