$\textbf{Giả thiết}$
$\text{$\widehat{A}$ + $\widehat{C}$ = $180^o$}$
$\text{$\widehat{B}$ + $\widehat{C}$ = $180^o$}$
$\textbf{Kết luận}$
$\text{$\widehat{A}$ = $\widehat{B}$}$
$\text{............................................................................................................}$
$\textbf{Giải}$
$\text{$\widehat{A}$ + $\widehat{C}$ = $180^o$ (gt)}$
$\text{$\widehat{B}$ + $\widehat{C}$ = $180^o$ (gt)}$
$\text{nên $\widehat{A}$ + $\widehat{C}$ = $\widehat{B}$ + $\widehat{C}$ (= $180^o$)}$
$\text{⇒ $\widehat{A}$ = $\widehat{B}$ }$
$\text{Vậy $\widehat{A}$ = $\widehat{B}$ (đpcm)}$
$\textit{HỌC TỐT!}$
$\text{NẾU CẦN HÌNH THÌ NÓI VỚI MÌNH!}$
