Draw a line segment AB of 4 cm in length. Draw a line perpendicular to AB through A and B, respectively. Are these lines parallel?
We know that if two lines are parallel, then the angle between them will be 0° or 180°.
Here, ∠XAB = 90°
And ∠YBA = 90°
∴ ∠XAB + ∠YBA = 90° + 90°
= 180°
So, the lines XA and YB are parallel.