Q.

For a cuboid with length (l), breadth (b) and height (h), which of the following statements are true

(i) Total surface area of the cuboid =2(lb+bh+lh) square units.

(ii) Diagonal of the cuboid has a length of l2+b2+h2 units.

(iii) If the cuboid was a room, the area of its walls would be (2l+2b+2h) square units.

(iv) All cuboids are cube.

Choose the correct option from the following:

1 (i) and (ii)
 
2 (ii) and (iii)
 
3 (i) and (iv)  
4 (ii) and (iv)  

Ans.

(1)

(i) Total surface area =Sum of areas of all faces =lb+bh+lh+bh+lh+lb=2(lb+bh+lh) 

(ii) Diagonal length =l2+b2+h2

The diagonal joins two opposite vertices of the cuboid.

(iii) Sum of the areas of the walls =lh+bh+lh+bh=2hl+b

(iv) All cubes are cuboid but all cuboids are not cube.