Answer:
Use the corner of a piece of paper to ensure the lines create 90° angle.
Explanation:
When constructing a perpendicular line through a point of a line, we have to verify that the lines constructed are perpendicular.
When we are going to draw a perpendicular line on another line at a point with help of a compass or using a protector, there may be some error in drawing and some error there can be in the perpendicular line.
So, the simple way to check whether the angles drawn are perfectly 90° or not is to use the corner of a piece of paper to ensure the lines create a 90° angle. (Answer)