\(\widehat{A}+\widehat{B}+\widehat{C}=180^o=>2.\widehat{C}+2.\widehat{C}+\widehat{C}=180^o\\ =>5.\widehat{C}=180^0\\ =>\widehat{C}=\dfrac{180^o}{5}=36^o\\ =>\widehat{A}=\widehat{B}=2.36^o=72^o\)
\(\widehat{A}+\widehat{B}+\widehat{C}=180^o\) ( tính chất tổng ba góc trong một tam giác )
\(\Rightarrow2.\widehat{C}+2.\widehat{C}+\widehat{C}=180^o\Rightarrow5.\widehat{C}=180^o\Rightarrow\widehat{C}=180^o:5=36^o\)
Vì \(\widehat{A}=\widehat{B}=2.\widehat{C}\)
\(\Rightarrow\widehat{A}=\widehat{B}=36^o.2=72^o\)
Vậy \(\widehat{A}=\widehat{B}=72^o\) và \(\widehat{C}=36^o\)