Show that the cone of the greatest volume which can be inscribed in a given sphere has an altitude equal to 2/3 of the diameter of the sphere.
Show that the cone of the greatest volume which can be inscribed in a given sphere has an altitude equal to 2/3 of the diameter of the sphere.

RD Sharma Solutions for Class 12 Maths Chapter 18 Maxima and Minima Image 67

Let the radius and height of cone be r and h respectively

\[Radius\text{ }of\text{ }sphere\text{ }=\text{ }R\]

\[{{R}^{2}}~=\text{ }{{r}^{2}}~+\text{ }{{\left( h\text{ }-\text{ }R \right)}^{2}}\]

\[{{R}^{2}}~=\text{ }{{r}^{2}}~+\text{ }{{h}^{2}}~+\text{ }{{R}^{2}}-\text{ }2hR\]

\[{{r}^{2}}~=\text{ }2hR\text{ }-\text{ }{{h}^{2}}~\ldots \text{ }\left( 1 \right)\]

Assuming volume of cone be $V$

RD Sharma Solutions for Class 12 Maths Chapter 18 Maxima and Minima Image 68

RD Sharma Solutions for Class 12 Maths Chapter 18 Maxima and Minima Image 69