a,b,c-laturi
b=c (Δ isoscel)
a,b,c dp cu 6,5,5
a/6=b/5=c/5=k
a=6k
b=5k
c=5k
a+b+c=128
6k+5k+5k=128
16k=128
k=8
a=48
b=40
c=40
A=√p(p-a)(p-b)(p-c)
p=(a+b+c)/2= (48+40+40)/2=128/2= 64
A=√64(64-48)(64-40)(64-40)
=√8² * 16 * 24 *24
=√8² * 4² *24²
=8*4*24
=768