Question

un dreptunghi are perimetrul de 300cm si latime de 3/7 din lungime. aflati aria dreptunghiului exprimata in dm²

Answer 1

P=l+l+L+L=30 dm
l=3L/7
3L/7+3L/7+L+L=30
3L+3L+7L+7L=210
20L=210
L=210:20
L=10.5

l=3*10.5/7
l=4.5

Aria=4.5*10.5
Aria=47.25

Answer 2

300cm=30dm

P=2l+2L=30

l=3/7 * L
l=3L/7

P=2*3L/7 + 2L=30
6L/7 + 2L=30 aducem la acelasi numitor

6L+14L=210
20L=210
L=10,5dm

l=3*10.5/7
l=31,5/7
l=4,5dm

A=L*l=10,5*4,5=47,25 dm²