(i) Given, \(AB|| DE\) and \(BC\) is a transversal line and \(\angle ABC=70\degree\)
\(\therefore ∠ABC = ∠DGC\) [Corresponding angles]
\(\therefore∠DGC =70\degree\) ……….(i)
(ii) Given, \(BC|| EF\) and \(DE\) is a transversal line and \(\angle DGC=70\degree\)
\(\therefore∠DGC = ∠DEF\) [Corresponding angles]
\(\therefore∠DEF = 70\degree\) [From eq. (i)]