Question 1141716
The diagonal of the square will be the same as 
the diameter of the circle
{{{ A = 25pi }}}
{{{ A = pi*r^2 }}}
{{{ 25pi = pi*r^2 }}}
{{{ r^2 = 25 }}}
{{{ r = 5 }}}
This is half the diameter, so
diameter = {{{ 10 }}}, and the 
diagonal also = {{{ 10 }}}
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Let {{{ x }}} = a side of the square
For a square
{{{ 10 = sqrt(2)*x }}}
{{{ x = 10/sqrt(2) }}}
{{{ x = 10*sqrt(2) / 2 }}}
{{{ x = 5*sqrt(2) }}}
and
Area of square = {{{ x^2 }}}
{{{ x^2 = 25*2 }}}
{{{ x^2 = 50 }}} mm2
get a 2nd opinion if needed