Question

Sa se afle aria dreptunghiului stiind : a). P=60cm, l=20% din perimetru
b).P=44cm., L=120% din l

Answer 1

1) 60 x 20/100=120/10=12 cm
   L=(60-2*12)/2=(60-24)/2=36/2=18
   Aria=12x18=216 cm²

b) 2x latimea +2 x 120% din latime =44  cm
     2 l + 12 l/5 = 44
     10 l +12 l = 44 x 5
      22 l = 44 x5
     l = 44x5/22= 10
     L= 10 x 120/100 = 12
Aria= 12 x 10 = 120 cm² 
  

Answer 2

l=20/100·60=12cm
P=2(L+l)
2(L+12)=60
L+12=60/2
L=30-12
L=18cm
A=Lxl
A=18x12=216 cm²
b) L=120/100xl=6xl/5
44=2(6xl/5+l)
2(6xl+5xl)/5=44
11xl/5=44/2
11xl/5=22
11xl=22x5
11xl=110
l=110/11
l=10
L=6x10/5=60/5=12
A=10x12=120cm²