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Q.
The radius of a right circular cylinder of greatest curved surface which can be inscribed in a given right circular cone is:
Application of Derivatives
Solution:
$\frac{ H }{ R }=\frac{ H - h }{ r }$
$S =2 \pi rh$
$=2 \pi H \left( r -\frac{ r ^2}{ R }\right)$
$\frac{ dS }{ dr }=2 \pi H \left(1-\frac{2 r }{ R }\right)$
Maximum at $r=\frac{R}{2}$