Question

Lungimea si latimea unui dreptunghi sunt direct proportionale cu 0,8(3) si0,375! Perimetrul egal cu 116 atunci aria este agla cu?

Answer 1

2L+2l=116
0,8(3)=83-8/90=75/90=15/18=5/6
0,375=375/1000=75/200=15/40=3/8
{L,l}dp:5/6,3/8}
6L/5=8l/3=k
6L/5=k ⇒L=5k/6
8l/3=k⇒  l=3k/8
2·5k/6+2·3k/8=116
5k/3+3k/4=116
(5k·4+3k·3)/12=116
20k+9k=116·12
29k=1392
k=1392/29
k=48
L=5k/6=(5·48)/6=40
L=40cm
l=3k/8=(3·48)/8=18
l=18cm
Aria=Lxl
aria=40x18=720cm²