Question

The length of a rectangular park is twice its breadth, and its perimeter measures 0.84 km. Find the area of the park in square metres.

Answer 1

Let the breadth of the rectangular park be$b$.
∴ Length of the rectangular park$=l=2b$
Perimeter = 0.84 km
$$\begin{gathered} \Rightarrow 0.84=2\left(l+b\right) \\ \Rightarrow 0.84=2\left(2b+b\right) \\ \Rightarrow 0.84=2\left(3b\right) \\ \Rightarrow 0.84=6b \\ \Rightarrow b=0.14\mathrm{km} \\ \Rightarrow b=0.14\times 1000\mathrm{m} \\ \Rightarrow b=140\mathrm{m} \\ \mathrm{Thus},\mathrm{we}\mathrm{have}: \\ l=2b \\ =2\times 140 \\ =280\mathrm{m} \end{gathered}$$

$$\begin{gathered} \mathrm{Area}=l\times b \\ =280\times 140 \\ =39200{\mathrm{m}}^2 \end{gathered}$$