bonjour
2 a + 2 b = 40 donc a + b = 20
ab = 40
a = 20 - b
( 20 - b ) b = 40
- b² + 20 b - 40 = 0
Δ = 20 ² - 4 ( - 1 * - 40 ) = 400 - 160 = 240 = 4 √15
x 1 = ( - 20 - 4 √15 ) / - 2 = 10 + 2 √15
x 2 = ( - 20 + 4 √15 )/ - 2 = 10 - 2 √ 15
2 ( 10 + 2 √15 + 10 - 2 √15 ) = 2 x 20 = 40
( 10 + 2 √15 ) ( 10 + 2 √15 ) = 100 - 60 = 40
donc longueur = 10 +2 √15 et largeur = 10 - 2 √ 15
