sir, please give me the proper solution with explation of following questions?
Q.A box with lid is made of wood which is 3 cm thick. It's external length,breadth and hieht are 56 cm,39 cm and 30 cm respectively.Find the capacity of the box.Also find the volume of wood used to make this box.
Q.If V is the volume of cuboid of dimension a,b and c and S is it's surface area , then prove that:-
1/v =2/s [1/a +1/b +1/c]
SOLUTION 1)
We have a cuboidal box with external dimensions (56cm x 39cm x 30cm)
The thickness of the wood in the box = 3 cm.
The box is open from one end.
∴ The internal dimensions are (50cm x 33cm x 27cm) as the box is considered to be open along its height at one end
The capacity of the box
Volume of wood
SOLUTION 2)
Volume of cuboid,V= abc ...........(i)
Surface area of cuboid,S= 2(ab+bc+ca) .......(ii)
Now, On Dividing (ii) by (i), we get,