CBSE Class 9 Answered

Can't read the question exactly.. but i suppose the question is as follows.

A building in the form of a right circular cylinder surrounded by a hemi. dome contains 880/21 cu m of air.If the total ht of the building = diameter of the building then height of the building=?

Ans-

Let the radius be r

 So diameter =2r

So, total height = 2r

So,

 height of the cylin + height of the hemi = 2r

This gives us theat thee height of the cylinder has to be r( as height of the hemi is its radius only which is r)

So,

acc to question and formul for volume of cylin and hemi.

 we  get,

[(22/7)(r*r*(r)]+[(2/3)(22/7)(r*r*r)]=880/21

Solving we get,

 r=2

So height of the building = diameter of the buliding=2r=4

So,

 Ans=4