Question

Find the surface area of a cube whose edge is
(i) 1.2 m
(ii) 27 cm
(iii) 3 cm
(iv) 6 m
(v) 2.1 m

Answer 1

$$\begin{gathered} \left(\mathrm{i}\right) \\ \mathrm{Edge}\mathrm{of}\mathrm{the}\mathrm{a}\mathrm{cube}=1.2\mathrm{m} \\ \therefore \mathrm{Surface}\mathrm{area}\mathrm{of}\mathrm{the}\mathrm{cube}=6\times (\mathrm{side}{)}^2=6\times (1.2{)}^2=6\times 1.44=8.64{\mathrm{m}}^2\mathrm{.} \\ \left(\mathrm{ii}\right) \\ \mathrm{Edge}\mathrm{of}\mathrm{the}\mathrm{a}\mathrm{cube}=27\mathrm{cm} \\ \therefore \mathrm{Surface}\mathrm{area}\mathrm{of}\mathrm{the}\mathrm{cube}=6\times (\mathrm{side}{)}^2=6\times (27{)}^2=6\times 729=4374{\mathrm{cm}}^2 \\ \left(\mathrm{iii}\right) \\ \mathrm{Edge}\mathrm{of}\mathrm{the}\mathrm{a}\mathrm{cube}=3\mathrm{cm} \\ \therefore \mathrm{Surface}\mathrm{area}\mathrm{of}\mathrm{the}\mathrm{cube}=6\times (\mathrm{side}{)}^2=6\times (3{)}^2=6\times 9=54{\mathrm{cm}}^2 \\ \left(\mathrm{iv}\right) \\ \mathrm{Edge}\mathrm{of}\mathrm{the}\mathrm{a}\mathrm{cube}=6\mathrm{m} \\ \therefore \mathrm{Surface}\mathrm{area}\mathrm{of}\mathrm{the}\mathrm{cube}=6\times (\mathrm{side}{)}^2=6\times (6{)}^2=6\times 36=216{\mathrm{m}}^2 \\ \left(\mathrm{v}\right) \\ \mathrm{Edge}\mathrm{of}\mathrm{the}\mathrm{a}\mathrm{cube}=2.1\mathrm{m} \\ \therefore \mathrm{Surface}\mathrm{area}\mathrm{of}\mathrm{the}\mathrm{cube}=6\times (\mathrm{side}{)}^2=6\times (2.1{)}^2=6\times 4.41=26.46{\mathrm{m}}^2 \end{gathered}$$