[tex]\Delta ABC \to \ iscoscel; \\ AB=AC \\ m(\ \textless \ BAC)=70^o \\ m(\ \textless \ ABC)=m(\ \textless \ ACB) \\ m(\ \textless \ ABC)+m(\ \textless \ ACB)=180^o-70^o=110^o \\ m(\ \textless \ ABC)=m(\ \textless \ ACB)=\frac{110^o}{2} \\ \Rightarrow \boxed{m(\ \textless \ ABC)=55^o}[/tex]
