Question

Mark the correct alternative in the following question:

The length of the diagonal of a square is 20 cm. Its area is

(a) 400 cm² (b) 200 cm² (c) 300 cm² (d) $100\sqrt{2}$ cm²

Answer 1

$$\begin{gathered} \mathrm{The}\mathrm{area}\mathrm{of}\mathrm{the}\mathrm{square}=\frac{1}{2}\times \mathrm{Diagonal}\times \mathrm{Diagonal} \\ =\frac{1}{2}\times 20\times 20 \\ =\frac{400}{2} \\ =200{\mathrm{cm}}^2 \end{gathered}$$

Hence, the correct alternative is option (b).