請幫忙證明以下數學題,謝謝!!?

Sol
在△CDF與△BCE中
∠DCF=90度－∠DCB=∠BCE
∠DFC=90度=∠BEC
△CDF～△CBE (AA)
CD/BC=CF/CE=DF/BE
AB/AD=CF/CE=DF/BE
AB/AD=DF/BE
AB*BE=AD*DF
AC^2=AF^2+CF^2
=(AD+DF)^2+CD^2－DF^2
=AD^2+2*AD*DF+DF^2+CD^2－DF^2
=AD^2+2*AD*DF+CD^2
=AD^2+AD*DF+AB*BE+AB^2
=AD(AD+DF)+AB(BE+AB)
=AD*AF+AB*AE