"An open tank with a   square base and vertical sides is to be constructed from a metal
Channel: Doubtnut
Date: 28/06/2020

"An open tank with a
 
  square base and vertical sides is to be constructed from a metal sheet so as
 
  to hold a given quantity of water. Show that the cost of the material will be
 
  least when depth of the tank is half of its width."