Question

Find the area of a square whose perimeter is 84 cm.

Answer 1

Let one side of the square be x cm.
Perimeter of the square = $(4\times \mathrm{side})=(4\times x)\mathrm{cm}=4x\mathrm{cm}$
It is given that the perimeter of the square is 84 cm.
$$\begin{gathered} \Rightarrow 4\mathrm{x}=84 \\ \Rightarrow x=\frac{84}{4}=21 \\ \mathrm{Thus},\mathrm{one}\mathrm{side}\mathrm{of}\mathrm{the}\mathrm{square}\mathrm{is}21\mathrm{cm}. \\ \mathrm{Area}\mathrm{of}the\mathrm{square}=(S\mathrm{ide}{)}^2=(21{)}^2{\mathrm{cm}}^2=441{\mathrm{cm}}^2 \end{gathered}$$