Question

An open box has an external breadth 12cm,length 15cm and height 10cm if the thickness of the material of the box is 1cm calculate the total surface area if the box. (hint there are 14 surfaces)​

Answer 1

1314 cm^2.

Explanation:

Area of the 5 external surfaces

= 12*15 + 2*12*10 + 2*15*10

= 720 cm^2.

The dimensions of the internal surfaces are

12 -2, 15-2 and 10 - 1

= 10,13 and 9 cm.

So their area

= 10*13 + 2 * 9*10 + 2*9*13

= 544 cm^2

The area of the top edges

= 2*15*1 + 2* 10*1

= 50 cm^2

So the Total Surface area

= 50 + 544 + 720

= 1314 cm^2.