Question

urgent! ajutati-ma la ex 19, 20, 21

Answer 1

19)
Pentru toate problemele:
L=lungimea
l=latimea
P=perimetru
/= fractie,impartit

l=2L/6
P/2=semiperimetru
P/2=1360
P=2(L+l)
2(L+l)/2=1360
L+l=1360
l=2L/6=L/3
L=3l
3l+l=1360
4l=1360
l=1360:4
l=340 m
L=3x340=1020 m
......................................
Acum aflam lungimea si latimea altui dreptunghi cu laturile numere consecutive impare si cu acelasi perimetru

P=2720
L=l+2
P=2(L+l)
2(L+l)=2720
L+l=2720:2
l+2+l=1360
2l+2=1360
2l=1360-2
2l=1358
l=1358:2
l=679 m
L=679+2=681 m
Deci latimea si lungimea sunt nr.impare consecutive
Verificare: 2(L+l)=2720
2(681+679)=2720
2x1360=2720

20)
2L/6=180⇒L=180x6:2=540 m
3l/5=90⇒l=90x5:3=150 m

L₁=lungimea altui dreptunghi
l₁=latimea altui dreptunghi
P₁=perimetru altui dreptunghi

L₁=L-l=540-150=390 m
l₁=390:3=130 m
P₁=2(L₁+l₁)=2(390+130)=2x520=1040 m

21)
L=lungime dreptunghi
l=latime dreptunghi
L₁=lungimea altui dreptunghi
l₁=latimea alpui dreptunghi
P₁=perimetru altui dreptunghi

L=4l
L₁=3L/4
l₁=l/2
P₁=1750
P₁=2(L₁+l₁)
P₁=2(3L/4+l/2)
P₁=2(3x4l/4+l/2)
2(3l+l/2)=1750
3l+l/2=1750:2
3l+l/2=875
6l+l=875x2
7l=1750
l=1750:7
l=250 m
L=4x250=1000 m
L₁=3L/4=3x1000:4=750 m
l₁=l/2=250/2=125 m

Sper ca te-am ajutat. Succes in comtinuare !!