Question

prameela painted the outer surface of a cabinet of measres 1m*2m*1.5m. find the surface area she cover if she painted all except the bottom of the cabinet?

Answer 1

Solution:-

Total surface area of the cuboid = 2(LB + BH + HL)
= 2(1*2 + 2*1.5 + 1.5*1)
= 2(2 + 3 + 1.5)
= 2*6.5
Total surface area = 13 sq m

Now, the bottom of the cabinet is not to be painted, so area of the bottom must be deducted from the total surface area.

Area of the bottom part of the cabinet = 1*2
= 2 sq m

Surface area of the cabinet covered by paint except the bottom part = 13 - 2 
= 11 sq m

Answer.

Answer 2

Solution:

l = 2 m, b = 1.5 m, h = 1 m

Area of the surface to be painted = Total surface area of box – Area of base of box

= 2 [lb + bh + hl] – lb

= 2[2 × 1.5 + 1.5 × 1 + 1 × 2] – 2 × 1

= 2[3 + 1.5 + 2] – 2

= 2[6.5] – 2

= 13 – 2

= 11 m2

Hence, the required area = 11 m2.