a/ Xét \(\Delta APE;\Delta APH\) có :
\(\left\{{}\begin{matrix}\widehat{APE}=\widehat{APH}=90^0\\PE=PH\\APchung\end{matrix}\right.\)
\(\Leftrightarrow\Delta APE=\Delta APH\left(ch-cgv\right)\)
\(\Leftrightarrow AE=AH\)
b/ Xét \(\Delta AHQ;\Delta AFQ\) có :
\(\left\{{}\begin{matrix}\widehat{AQH}=\widehat{AQF}=90^0\\HQ=QF\\QAchug\end{matrix}\right.\)
\(\Leftrightarrow\Delta AHQ=\Delta AFQ\left(c-g-c\right)\)
\(\Leftrightarrow AH=AF\left(2\right)\)
Từ \(\left(1\right)+\left(2\right)\Leftrightarrow AE=ÀF\)