Theory:

There are many places where we are see the perpendicular lines and parallel lines in our real life.
 
Just check out the following collage.
 
collage2.jpg
 
Let us discuss the perpendicular cases:
  • The sides of the soccer field with the centre lines
  • Television screen with its edges
  • Some grills in the window design
  • Railway track crossing
  • Sign of the first aid kit
Let us check the definition of perpendicular line with an example:
Two different lines intersecting each other at right angle or \(90°\) are called perpendicular lines.
shutterstock_402381289.jpg
 
Let us check some more examples:
 
45badf9bf2262efb8adc8952e0ad0886_collage1_450.jpg
 
Let us discuss some of the parallel cases:
  • Lines in the race field
  • Railway track
  • Cars in the queue
  • Steel rack shelves
  • Sides of the road
Two lines are parallel when they do not intersect each other at any point on the plane. 
parallel lines-w1278.png
Set Square:
Two triangular instruments in the geometry box are called as 'Set square'.
  • Both the set squares has right angles in it.
  • One of the set squares is an isosceles triangle with two angles measuring \(45°\) on the equal sides.
  • Other set square is a scalene triangle with two angle measuring \(30°\) and \(60°\).
shutterstock_1552389098.jpg
 
Uses of Set square:
  • To construct the specific angles \(90°\), \(45°\), \(30°\) and \(60°\).
  • To draw parallel and perpendicular lines.
  • To measure the height.