Cho tam giác \(ABC\)  có \(AB < AC\) . Gọi \(E \in AC\) sao cho \(AB = CE\). Gọi \(O\)  là một điểm nằm ở trong tam giác sao cho \(OA = OC,OB = OE.\) Khi đó:

\(\Delta AMC = \Delta BCM\)

\(AM \bot BC\)

\(\widehat {BAM} = \widehat {CAM}\)     

\(\Delta AMB = \Delta AMC\)

\(AB = MN\) 

$AC = NP$   

\(\widehat A = \widehat M\) 

\(\widehat P = \widehat C\)

50\(^\circ \)

40\(^\circ \)

70\(^\circ \)

80\(^\circ \)

\(\widehat D = 33^\circ \) 

\(\widehat D = 42^\circ \)   

\(\widehat E = 32^\circ \) 

\(\widehat D = 66^\circ \)

\(\Delta ABC = \Delta CDA\)

\(\widehat {ABC} = \widehat {CDA}\)        

\(\widehat {BAC} = \widehat {DAC}\)        

\(\widehat {BCA} = \widehat {DAC}\)

\(\widehat A = \widehat D = 65^\circ ;\,\widehat C\, = \widehat F = 50^\circ .\)

\(\widehat A = \widehat D = 50^\circ ;\,\widehat C\, = \widehat F = 65^\circ .\) 

\(\widehat A = \widehat D = 75^\circ ;\,\widehat C\, = \widehat F = 50^\circ .\) 

\(\widehat A = \widehat D = 50^\circ ;\,\widehat C\, = \widehat F = 75^\circ .\)

\(\Delta ABC = \Delta DEF\) 

\(\Delta ABC = \Delta EFD\)   

\(\Delta ABC = \Delta FDE\) 

\(\Delta ABC = \Delta DFE\)