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AP EAMCET · Maths · Application of Derivatives

A closed cylinder of given volume will have least surface area when the ratio of its height and base radius is

  1. A 2:1
  2. B 1:2
  3. C 2:3
  4. D 3:2
Verified Solution

Answer & Solution

Correct Answer

(A) 2:1

Step-by-step Solution

Detailed explanation

For a closed cylinder let the height be h and base radius be r. Volume, V=πr2h i.e. h=Vπr2 Now, surface area, S=2πrh+2πr2=2πrVπr2+2πr2 =2Vr+2πr2 For least surface area, dSdr=0 ⇒-2Vr2+4πr=0⇒V=2πr3 Hence,…