Question

a worker is putting insulation into the roof above an L shaped building as shown below. specifications call for one-metre of insulation throughout. 8cm, 18cm and 25cm, 8cm. how many cubic meters of insulation is required for the job?

Answer 1

Lets calculate the total area. We have a rectangle of sides 8+18 = 26 m and 8+25 = 33 m. So:

$\begin{gathered} \text{area=26}\times33 \\ \text{area =858m}^2 \end{gathered}$

The "ghost area" is a rectangle of sides 25 m and 18 m. The area will be:

$\begin{gathered} \text{area}=25\times18 \\ \text{area}=450m^2 \end{gathered}$

So the L-shaped area is:

$L-shapedarea=858-450=408m^2$

To get the volume just multiply the result above by 1 m, which is the height of insulation:

$\begin{gathered} \text{volume =408}\times1 \\ \text{volume =408m}^3 \end{gathered}$

Answer: it is required 408 cubic meters for the job.