Question:
In the figure, ∠1 = 60° and ∠6 = 120°. Show that the lines m and n are parallel.
Solution:
Given In the figure ∠1 = 60° and ∠6 = 120°
To show m||n
Proof Since, ∠1 = 60° and ∠6 = 120°
Here, ∠1 = ∠3 [vertically opposite angles]
∠3 = ∠1 = 60°
Now, ∠3 + ∠6 = 60° + 120°
=> ∠3 + ∠6 = 180°
We know that, if the sum of two interior angles on same side of l is 180°, then lines are parallel.
Hence, m || n