![](https://hoc24.vn/images/avt/avt74271_60by60.jpg)
![](https://hoc24.vn/images/avt/avt60480_60by60.jpg)
![](https://hoc24.vn/images/avt/avt178590_60by60.jpg)
![](https://hoc24.vn/images/avt/avt117537_60by60.jpg)
![](https://hoc24.vn/images/avt/avt36305_60by60.jpg)
![](https://hoc24.vn/images/avt/avt98655_60by60.jpg)
![](https://hoc24.vn/images/avt/avt203854_60by60.jpg)
![](https://hoc24.vn/images/avt/avt210131_60by60.jpg)
![](https://hoc24.vn/images/avt/avt169397_60by60.jpg)
![](https://hoc24.vn/images/avt/avt98655_60by60.jpg)
![](https://hoc24.vn/images/avt/avt74271_60by60.jpg)
![](https://hoc24.vn/images/avt/avt36305_60by60.jpg)
![](https://hoc24.vn/images/avt/avt203854_60by60.jpg)
![](https://hoc24.vn/images/avt/avt178590_60by60.jpg)
![](https://hoc24.vn/images/avt/avt26545_60by60.jpg)
![](https://hoc24.vn/images/avt/avt60480_60by60.jpg)
![](https://hoc24.vn/images/avt/avt23379_60by60.jpg)
![](https://hoc24.vn/images/avt/avt206972_60by60.jpg)
![](https://hoc24.vn/images/avt/avt153928_60by60.jpg)
Xét tam giác ABC có:
\(\widehat{A}+\widehat{B}+\widehat{C}=180^o\)
\(\Rightarrow\widehat{C}=180^o-\widehat{A}-\widehat{B}\)
\(=180^o-60^o-70^o=50^o\)
Vì D và E lần lượt là trung điểm của AB và AC
=> DE là đường trung bình của tam giác ABC
=> DE//BC
=> DECB là hình thang
Vì DECB là hình thang nên \(\widehat{D}+\widehat{B}=180^o\)
\(\Rightarrow\widehat{D}=180^o-\widehat{B}=110^o\)
Tương tự : \(\widehat{E}=180^o-\widehat{C}=130^o\)