How are scale drawings used in everyday life?

One of the most useful cases where scaling is very important is through the use of Maps. May it be a city map, country map, or world map, it won't be practical to draw the map with the real measurements of the streets, etc. That is why their are drawn to scales. 

The distance from point a to point c across the coordinate plane is aproxamatly 8.94 rounded to the nearest hundredth. you use a^2 + b^2 =c^2