[tex]\it \mathcal{P} =2(L+\ell) =180|_{:2} \Rightarrow L+\ell = 90\ \ \ (1)[/tex]
[tex]\it \ell = \dfrac{2}{3}L \ \ \ (2)[/tex]
[tex]\it (1), (2) \Rightarrow L+\dfrac{2}{3}L = 90 \Rightarrow 3L+2L = 270 \Rightarrow 5L = 270|_{:5} \Rightarrow L= 54 cm[/tex]
[tex]\it \ell = \dfrac{2}{3}\cdot 54 = 36 cm[/tex]
Deci, dimensiunile dreptunghiului sunt:
L = 54 cm, l =36 cm .
