bonjour
soient a et b la longueur et la largeur du rectangle
2 a + 2 b = 25
ab = 25
a + b = 12.5
a = 12.5 - b
ab = ( 12.5 - b ) b = 25
- b² + 12.5 b - 25 = 0
Δ = 12.5² - 4 ( - 1 * - 25 ) = 156.25 - 100 = 56.25 = 7.5 ²
x 1 = ( - 12.5 - 7.5 ) / - 2 = - 20 / - 2 = 10
x 2 = ( - 12.5 + 7.5 ) / - 2 = - 5 / -2 = 2.5
longueur = 10 et largeur = 2.5
