Question 1178511
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{{{Total area = r(x-r) + x(y-r) + (pi/4) r^2}}}

A= xr - r^2 +xy -xr +(pi/4) r^2


A = xy -r^2 +(pi/4)r^2

A = xy -r^2 (1-(pi/4))

A= xy -r^2 ( (4-pi)/4))
 
{{{r^2 ( (4-pi)/4)) =xy-A}}}

{{{r^2 = (xy-A)/(((4-pi)/4))}}}

{{{r^2 = 4*(xy-A) / (4-pi)}}}

{{{r= 2* sqrt((xy-A)/(4-pi))}}}