start: isos triangel, rim leng=2 ft, sides 2 inch longer than base
rim leng=3*base+2inch+2inch
3*base=24inch-4inch=20
base=20/3=6.66666
side=(20/3)+2=8.66666
hite=vertikal line from base...hite^2+(base/2)^2=side^2
side^2=8.6666^2=44.44444
(base/2)=3.33333 ; square=11.11111
hite^2=44.4444 - 11.1111=33.3333
hite=5.77350266
area=base*hite/2=19.243