Question

What is the total surface area where the length is 20cm, breadth 15 cm, height 10 cm. without the top of the cuboid.

Answer 1

Surface area of cuboid =$2(lb+bh+lh)$
Surface area of top = $lb$
Required surface area= surface area of cuboid - surface area of top
Required surface area= $2(lb+bh+lh)-lb$
=$2(20\times 15+15\times 10+10\times 20)-(20\times 15)$
=$2(300+150+200)-300$
=$2\left(650\right)-300$
=$1300-300$
= $1000c{m}^2$​