Question

What is the area of circle whose radius is diagonal of a square whose area is 4?

Answer 1

square area = 4
length of each side is 2
by pythagoras theorem....diagonal length is $\sqrt{8}$
radius = $\sqrt{8}$
area of circle  = $\pi$$r^{2}$
25.132

Answer 2

Given ,

Area of square = 4
we know that ,
  Area of square = (side of square )*(side of square )
therefore ,
 (side of square )*(side of square ) = 4
 (side of square )*(side of square ) = 2 *2
 side of square = 2.

we also know that ,


   diagonal of square  = side* square  root of 2 .
                   = 2* Square root of 2.

from the given problem ,

   radius of circle = diagonal of square


area of circle  = 22/7 * radius *radius
                = 22/7 *2*square root of 2 * 2*square root of 2.
                = 22/7 *2*2*2
        = 22*8/7
        =  25.12