A wire of length 2 units is cut into two parts which are bent respectively to form a square of side = x…

A wire of length 2 units is cut into two parts which are bent respectively to form a square of side =x units and a circle of radius =r units. If the sum of the areas of the square and the circle so formed is minimum, then
  1. x=2r
  2. 2x=r
  3. 2x=π+4r
  4. 4-πx=πr

Solution




Given that 4x+2πr=2

i.e., 2x+πr=1

r=1-2xπ .......(i)

Area A=x2+πr2

=x2+1π 2x-12

For min vale of area A

dAdx=0 gives x=2π+4 .......(ii)

From (i) and (ii)

r=1π+4 .......(iii)

x=2r

Asked in: JEE Main 2016 (03 Apr)

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