Question

In figure, $\angle 1={60}^o$ and $\angle 6={120}^o$. Show that the lines $m$ and $n$ are parallel.

Answer 1

We have,

$\angle 5+\angle 6={180}^0$ [linear pair Angles]

$\Rightarrow \angle 5+{120}^0={180}^0\Rightarrow \angle 5={180}^0-{120}^0={60}^0$

Now, $\angle 1=\angle 5$ [Each $={60}^0$]

But, these are corresponding angles.

Therefore, the lines $m$ and $n$ are parallel.