Giải thích các bước giải:
b.Xét $\Delta AMC, \Delta EMB$ có:
$MA=ME$
$\widehat{AMC}=\widehat{BME}$(đối đỉnh)
$MC=MB$
$\to \Delta MAC=\Delta MEB(c.g.c)$
$\to \widehat{MAC}=\widehat{MEB}$
$\to AC//BE$
d.Xét $\Delta AMB,\Delta CME$ có:
$MB=MC$
$\widehat{AMB}=\widehat{CME}$
$MA=ME$
$\to\Delta AMB=\Delta EMC(c.g.c)$
$\to \widehat{ABM}=\widehat{MCK}\to \widehat{IBM}=\widehat{MCK}$
Xét $\Delta BMI,\Delta CMK$ có:
$MB=MC$
$\widehat{MBI}=\widehat{MCK}$
$BI=CK$
$\to \Delta BMI=\Delta CMK(c.g.c)$
$\to \widehat{IMB}=\widehat{CMK}$
$\to I,M,K$ thẳng hàng