Question

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

• A. 220 $c{m}^2$
• B. 240 $c{m}^2$
• C. 200 $c{m}^2$
• D. 215 $c{m}^2$

Answer 1

The correct option is D

215 $c{m}^2$

Surface area of the figure = sum of areas of (I + II + III + IV + V)

$=(15\times 3.5)+(5\times 3.5)+(15\times 3.5)+(5\times 3.5)+(15\times 5)$

$=215c{m}^2$

Alternate solution

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

Therefore surface area = 2(lb+ bh + lh) – lb = lb + 2h(l+b)

$=(15\times 5)+7\left(20\right)=215c{m}^2$