If we look at the real life examples, edges of adjacent sides of windows, adjacent sides of door, adjacent sides of two walls represent the pair of Perpendicular Lines.

In case we have a pair of lines such that two angles are equal and pair of angles form a linear pair, then we say that common Ray between two angles is perpendicular line on two uncommon rays, which represent the Straight Line. If we look at English alphabets, we find that alphabet T, L, E, H , F all represent the Set of perpendicular lines. If we look at the adjacent sides of geometrical figures like Square and Rectangle, we say that they are perpendicular to each other. On the contrary, we also observe that pair of diagonals of square and Rhombus also represent the pair of perpendicular lines. If we look at sign of Addition “ + “, or doctors / Ambulance sign, it is also the pair of the two perpendicular lines crossing each other.