1. When making maps and engineering plans, we must first determine the scale, and the scale = distance on the map/actual distance.

2. Once the scale is determined, such as a, the length of the plan and the length of the width (the distance on the plan) can be calculated according to the above.

For example, your ratio can be defined as: 1:200, then the length and width of the rectangular plane are as follows:

Length =12m * (1:200) =1200m * (1:200) = 6cm.

Width =10m *( 1:200)= 1000 cm * (1:200) = 5cm.

3. Draw a rectangle with the length and width of 6 cm and 5 cm respectively on the plan, and the scale on the legend is marked as: 1: 200.