In figure, find the values of x and y and then show that AB ||CD.

\(\because \) x + 50° = 180° .....(Linear pair)
\(\Rightarrow \) x = \(130^\circ\)
\(\therefore \) y = \(130^\circ\) .....(vertically opposite pair)

Here, these are corresponding angles for lines AB and CD.

Hence, it is proved that AB || CD.