Đặt \(\widehat{A}=a;\widehat{B}=b;\widehat{C}=c\)
Theo đề, ta có: a/3=b/25
=>b/25=a/3
\(\Leftrightarrow b=25\cdot\dfrac{a}{3}=\dfrac{25}{3}a\)
Ta có: a+b+c=180
=>a+25/3a+4a=180
=>40/3a=180
=>a=13,5(độ)
=>\(\widehat{B}=\dfrac{25}{3}\cdot13.5=112.5^0\)
\(\widehat{C}=4\cdot13.5^0=54^0\)