Question

Lungimea si latimea unui dreptunghi sunt direct  proportionale cu numerele 0,8(3) si 0,375. Stiind ca perimetrul este egal cu 116 cm , calculati aria sa.

Answer 1

0,8(3)=(83-8):90=75/90=15/18=5/6
0,375=3/8
L/ (5/6)=l/(3/8)=(L+l)/(5/6+3/8) proportiiderivate
L+l=Perim:2=116:2=58
5/6+3/8=20/24+9/24=29/24
relatia de mai sus devine
6L/5=8l/3= 58: (29/24)=58*24/29
 6L/5=8l/3=48

6L/5=48
L/5=8
L=40


8l/3=48
l/3=6
l=18

( verificare 2(40+18)=2*58=116 si 40/18=5/6:3/8=5/6*8/3=20/9 laturile sunt bine calculate)

Aria =L*l=40*18=720cm²