CBSE Class 12-science Answered
In this question we see the radius of sphere is constant R. So we shall assume sphere is fixed. Also cylinder inside the sphere is variable. We need to find the dimensions of cylinder, which makes this of maximum volume.
Consider the cylinder of radius r and height h so its volume becomes
Now from figure AB = h so that
So we get
Using this the volume becomes
Assuming to be constant we differentiate with respect to we get
For maximum or minimum value
To check whether this is a point of local maxima or minima we differentiate once again with respect to h
which of course is negative
So is a point of maxima
Hence volume of cylinder is maximum when its height is times the radius of outer sphere.