Question 750963
h=8-height 
b-base
a-the isosceles sides
perimeter is 25 means: 

{{{b+2a=25}}}

and

{{{(b/2)^2+h^2=a^2}}}

or 

{{{(b^2)/4+64=a^2}}}

so that 


{{{(b^2)/4+64=((25-b)/2)^2}}}



and thus after some algebra we get

b=369/50




:)