in caz ca e la dreptunghi....
l[tex] \frac{l}{L} [/tex] = [tex] \frac{2}{3} [/tex]
=>3l = 2L
=>l = [tex] \frac{2L}{3} [/tex]
P = 2(l + L)
P = 2([tex] \frac{2L}{3} [/tex] + L)...amplifici cu 3 la toate in afara de fractie
3P = 2L + 3L
3x100 = 5L
150 = 5L...imparti la 5
=>30 = L
l = [tex] \frac{2L}{3} [/tex]
l = [tex] \frac{2x30}{3} [/tex]
l = 20