Question 172291
Let's see the Isosceles Triangle:
{{{drawing(400,400,-4,4,-1.5,9,triangle(-3,0,0,8,3,0),locate(-2,5,a=x),locate(2,5,a=x),locate(-1,-.5,b=x+x-4),red(locate(-.5,-.90,b=34ft)),red(locate(2,4,a=19ft)),red(locate(-3,4,a=19ft))))}}}

It follows: {{{P[T]=2a+b}}}
Since Perimter is between 0-75ft, we take {{{P=72ft}}}. Then,
{{{72ft=2x+x+x-4}}}
{{{72+4=4x}}}
{{{76=4x}}} ---------->{{{cross(76)19/cross(4)=cross(4)x/cross(4)}}}
{{{highlight(x=19ft)}}} =a, The 2 equal sides
For the base:
{{{b=19+19-4=38-4=34ft}}}
Check:
{{{72=2*19+34}}}
{{{72=38+34}}}
{{{72ft=72ft}}}
*Note: The computed values are based on taking the Perimeter as 72ft. Try max 75ft?
Thank you,
Jojo