Question

repede! sa se afle aria unui dreptunghi care are P= 60cm si l= 20% din P.

Answer 1

l = 60x20/100 = 60x1/5 = 12 cm ; aflam L

60 = 2(L+l) ; 30 = L+12 ; L = 30-12 = 18 cm ;

A = Lxl = 18x12 = 216 cm²

Answer 2

l=20% din 60 = 20/100 × 60 = 20×60/100 = 1200/100 = 12 cm

P=2(L+l)

60 = 2(L+12)

60 = 2L + 24

2L = 60 - 24

2L = 36  ⇒  L = 36/2 = 18 cm

A = L×l

A = 18×12

A = 216 cm²