a) Ta có AB > AC, do đó $\widehat{ACB}>\widehat{ABC}$ suy ra $\widehat{ACN}<\widehat{ABM}$
Vậy $\widehat{ANC}> \widehat{AMB}$
b) Trong tam giacs ANM, ta cos $\widehat{ANC}>\widehat{AMB}$, suy ra AM> AN.
a) Ta có AB > AC, do đó $\widehat{ACB}>\widehat{ABC}$ suy ra $\widehat{ACN}<\widehat{ABM}$
Vậy $\widehat{ANC}> \widehat{AMB}$
b) Trong tam giacs ANM, ta cos $\widehat{ANC}>\widehat{AMB}$, suy ra AM> AN.