Question

Answer 1

\(\widehat{A}+\widehat{B}=120^o\\ \Rightarrow\widehat{A}=120^o-\widehat{B}\)

\(3\widehat{B}-2\widehat{A}=10^o\\ \Rightarrow3\widehat{B}-2\left(120^o-\widehat{B}\right)=10^o\\ \Rightarrow3\widehat{B}-240^o+2\widehat{B}=10^o\\ \Rightarrow5\widehat{B}=250^o\\ \Rightarrow\widehat{B}=50^o\)

\(\widehat{A}=120^o-\widehat{B}=120^o-50^o=70^o\)

Xét \(\Delta\)ABC ta có:

\(\widehat{A}+\widehat{B}+\widehat{C}=180^o\\ \Rightarrow120^o+\widehat{C}=180^o\\ \Rightarrow\widehat{C}=60^o\)