Answer: congruent sides have equal legnth
the shorter side is the last side
if the congruent sides are x and the shorter one is y, and x is 1 longer than y then
x=1+y
perimiter=x+x+y
x=1+y
perimiter=1+y+1+y+y=3y+2
square is 4s
each side (s) is 2 less than y
s=y-2
square is 4(y-2)=4y-8
4y-8=3y+2
minus 3y both sides
y-8=2
add 8 both sides
y=10
the legnth is 10 units