Question

giúp em gấp với huhu

Answer 1

\(BC=\sqrt{AB^2+AC^2}=\sqrt{3,5^2+4,2^2}=\dfrac{7\sqrt{61}}{10}cm\left(Pyatgo\right)\)

\(\sin\widehat{C}=\dfrac{AB}{BC}=\dfrac{3,5}{\dfrac{7\sqrt{61}}{10}}\simeq39^0\)

\(\Rightarrow\widehat{B}=\widehat{A}-\widehat{C}=90^0-39^0=51^0\)