Question

Q-2

2. The surface area of a cuboid is 758 cm² .Its length and breadth are 14 cm and 11 cm respectively . Find its height.

Answer 1

$$\begin{gathered} \mathrm{Let}\mathrm{l},\mathrm{b}\mathrm{and}\mathrm{h}\mathrm{be}\mathrm{the}\mathrm{length},\mathrm{breadth}\mathrm{and}\mathrm{height}\mathrm{of}\mathrm{the}\mathrm{cuboid}\mathrm{respectively}. \\ \mathrm{Now},\mathrm{l}=14\mathrm{cm};\mathrm{b}=11\mathrm{cm};\mathrm{h}=? \\ \mathrm{Now},\mathrm{TSA}=758{\mathrm{cm}}^2 \\ \Rightarrow 2\left(\mathrm{lb}+\mathrm{bh}+\mathrm{hl}\right)=758 \\ \Rightarrow 2\left[14\times 11+11\mathrm{h}+14\mathrm{h}\right]=758 \\ \Rightarrow 154+25\mathrm{h}=379 \\ \Rightarrow 25\mathrm{h}=379-154 \\ \Rightarrow 25\mathrm{h}=225 \\ \Rightarrow \mathrm{h}=\frac{225}{25}=9\mathrm{cm} \end{gathered}$$