What is the area of a square parcel of land with 10cm. side on a cadastral map of 1:4000 scale?
\[
MS = \frac{MD}{GD}
\]
\[
\frac{1}{4000} = \frac{10cm.}{GD}
\]
\[
GD = 40000cm. (\frac{1m.}{100cm.})
\]
\[
GD = 400m.
\]
\[
A = a^2
\]
Let:
$GD = a$
\[
A = (GD)^2
\]
\[
A = 160000sqm.
\]
\[
A = 16ha. \leftarrow \text{answer}
\]