Question 964894
Dimensions, x and y.


Handling as if for a rectangle,



{{{system(2x+2y=30,xy=30)}}}


{{{system(x+y=15,xy=30)}}}


{{{y=15-x}}};
{{{x(15-x)=30}}}
{{{15x-x^2=30}}}
{{{15x-x^2-30=0}}}
{{{-15x+x^2+30=0}}}
{{{x^2-15x+30=0}}}
-
{{{15^2-4*30=105}}}


{{{x=(15+- sqrt(105))/2}}}


{{{x=2.38}}}  or  {{{x=12.62}}}
{{{y=12.62}}}  or  {{{y=2.38}}}


The question seems open enough for other figures, but a rectangle is a valid possibility.