Question

Find the surface area of the following figure if it is folded along the dotted lines. (all the measurements are in cm)

Answer 1

Upon folding we get a cuboid excluding one of the top or bottom faces

Therefore surface area = 2(lb+ bh + lh) – lb
where l = 15 cm, b = 5 cm, and h = 3.5 cm.

$\begin{array}{cc}\therefore \text{Surface area}& =lb+2h(l+b)\\ & =(15\times 5)+[2\times 3.5(20\left)\right]\\ & =75+140\\ & =215c{m}^2\end{array}$

Hence, the required surface area is $215c{m}^2$.