Theo bài ra ta có: \(\widehat{A}=2\widehat{B};\) \(\widehat{B}=2\widehat{C}\)
suy ra: \(\widehat{A}=4\widehat{C};\)
Ta có: \(\widehat{A}+\widehat{B}+\widehat{C}=180^0\)
<=> \(4\widehat{C}+2\widehat{C}+\widehat{C}=180^0\)
<=> \(7\widehat{C}=180^0\)
<=> \(\widehat{C}=\frac{180^0}{7}\)
ĐẾN ĐÂY TÍNH NỐT NHA