Đáp án:
$\begin{array}{l}
AB < AC\\
\Rightarrow \widehat {ACB} < \widehat {ABC}\\
\Rightarrow - \widehat {ACB} > - \widehat {ABC}\\
hay\, - \widehat {DCB} > - \widehat {EBC}\\
\Rightarrow {90^0} - \widehat {DCB} > {90^0} - \widehat {EBC}\\
\Rightarrow \widehat {DBC} > \widehat {ECB}\\
\end{array}$
$\begin{array}{l}
hay\,\widehat {HBC} > \widehat {HCB}\\
\left( {do:H \in BD;H \in EC} \right)\\
Trong:\Delta HBC:\\
\widehat {HBC} > \widehat {HCB}\\
\Rightarrow HC > HB
\end{array}$