Question

in the adjacent figure,‘l’ is a transversal of AB and CD than prove that AB||CD​

Answer 1

Proof:-

<AFE + 55° = 180° (straight line)

<AFE= 180°- 55°

<AFE= 125°

similarly

<CEF + 125°=180°

<CEF= 55°

Now, <AFE+ <CEF= 125°+55°= 180°

therefore,

AB//CD (Sum of same side of interior angle in parallel lines is equal to 180°)