Following are the steps of Construction:
(i) Construct a line AB = 12 cm.
(ii) Take M as the midpoint of line AB.
(iii) Construct straight lines CD and EF which is parallel to AB at 3 cm distance.
(iv) Taking M as centre and 5 cm radius construct areas which intersect CD at P and Q and EF at R and S.
(v) Now join QR and PS.
now,
PQRS is a rectangle where the length
\[PQ\text{ }=\text{ }8\text{ }cm\]
So the area of rectangle PQRS = PQ × RS
We get
\[\begin{array}{*{35}{l}}
=\text{ }8\text{ }\times \text{ }6 \\
=\text{ }48\text{ }c{{m}^{2}} \\
\end{array}\]