_Xét △ABC ta có:
\(\widehat{A}\) + \(\widehat{B}\) + \(\widehat{C}\) = 180o
=> 50o + \(\widehat{B}\) + \(\widehat{C}\) = 180o
=> \(\widehat{B}\) + \(\widehat{C}\) = 180o \(-\) 50o
=> \(\widehat{B}\) + \(\widehat{C}\) = 130o : 2 = 65o
=> \(\widehat{B}\) = \(\widehat{C}\) = 65o
=> \(\widehat{A}\) < \(\widehat{B}\) => BC < AB
Vậy trong △ABC có:
BC < AB