Question

L/l=3/7 perimetul=12,5cm, care este aria?

Answer 1

L/ l =3/7  ; l =7L/3
P =2L+2 l
12.5 =2L +2*7L/3
12.5 =2L+14L/3
37.5 =6L+14L
20L =37.5
L =37.5 /20 =1.875 cm
l =7*1.875/3 =4.375 cm
A =1.875 *4.375 =8.20 cm ^2

Answer 2

L/l=3/7
L=3l/7
A=L•l=3l/7•l=3l^2/7
P=2(L+l)=12,5 cm
L+l=12,5 cm/2=6,25 cm
3l/7+7l/7=10l/7=6,25 cm
10l=6,25 cm•7=43,75 cm
l=43,75 cm/10=4,375 cm
L=3•4,375 cm/7=1,875 cm
A=1,875 cm•4,375 cm=8,2 cm^2