Perim.=c₁+c₂+i
i=30
c₁-c₂=6 =>c₁=6+c₂
P=6+c₂+c₂+30
P=2c₂+36
P=2(c₂+18)
T.Pit. spune ca c₁²+c₂²=900
(6+c₂)²+c₂²=900
36+12c₂+c₂²+c₂²=900
2c₂²+12c₂-864=0 l:2
c₂²+6c₂-432=0
Δ=36+4·432
Δ=36+1728
Δ=1764 =>√Δ=42
=>c₂=18 cm (n-am luat in considerare valoarea negativa a lui c₂)
=>c₁=24
=>P=24+18+30
=>P=72 cm
