Construct a quadrilateral BDEF, where DE = 4.5 cm,

Steps of construction:

Step I : Draw $\mathrm{EF}=3.5 \mathrm{~cm}$.

Step II : Construct $\angle \mathrm{DEF}=100^{\circ}$ at $\mathrm{E}$.

Step III : With $\mathrm{E}$ as the centre and radius $4.5 \mathrm{~cm}$, cut off $\mathrm{DE}=4.5 \mathrm{~cm}$.

Step IV : Construct $\angle \mathrm{EFB}=50^{\circ}$ at F.

Step V : With F as the centre and radius $6.5 \mathrm{~cm}$, cut off $\mathrm{FB}=6.5 \mathrm{~cm}$.

Step VI : Join BD.

The quadrilateral so obtained is the required quadrilateral.