[tex]m(\hat{A})=80\Rightarrow m(\hat{B})=m(\hat{C})=\dfrac{180-80}{2}=50\\
m(\hat{B})=30\Rightarrow m(\hat{C})=30 \Rightarrow m(\hat{A})=180-30-30=120\\
m(\hat{C})=45\Rightarrow m(\hat{B})=45 \Rightarrow m(\hat{A})=180-45-45=90\\
m(\hat{A})=66 \Rightarrow m(\hat{B})=m(\hat{C})=\dfrac{180-66}{2}=57[/tex]