To find the actual height of the building using the given scale, you can use the following relationship:
1 cm on the drawing = 0.5 meters in reality.
If the height of the building in the drawing is 18 cm, you can calculate the actual height as follows:
\[ \text{Actual height} = \text{Height in drawing} \times \text{Scale factor} \]
Substituting the values:
\[ \text{Actual height} = 18 \text{ cm} \times 0.5 \text{ meters/cm} = 9 \text{ meters} \]
Therefore, the actual height of the building is 9 meters.