Theo bài ra ta có : \(\dfrac{AB}{3}=\dfrac{BC}{5}=\dfrac{AC}{7}\)
=> AB > BC > AC
-Ta có: \(AB:BC:CA=3:5:7\)
\(\Rightarrow\dfrac{AB}{3}=\dfrac{BC}{5}=\dfrac{CA}{7}\)
\(\Rightarrow AB=\dfrac{3}{5}BC;BC=\dfrac{5}{7}CA\)
\(\Rightarrow AB< BC;BC< CA\)
\(\Rightarrow AB< BC< CA\)