Question

Rukhsar painted the outside of the cabinet of measure $1m\times 2m\times 1.5m$. How much surface area did she cover if she painted all except the bottom of the cabinet.​

Answer 1

The total surface area of the cuboidal cabinet $=2\times (lb+bh+lh)$
where $l,b,$ and $h$ are its length, breadth, and height respectively.

Total surface area $=2\times (2\times 1+1\times 1.5+2\times 1.5)$
$=2\times (2+1.5+3)m^2$
$=2\times 6.5m^2$
$=13m^2$
Area of the bottom surface $=l\times b$
$=2\times 1m^2$
$=2m^2$

The effective surface area that she has painted = Total surface area of the cabinet - Area of the bottom surface

Hence, the surface area painted by Rukhsar $=(13–2)=11m^2$