Bonsoir,
a) Rappel formule aire rectangle :
A = Longueur x largeur
Donc :A = x * 9/8x * = signe multiplié
A = (8 * 8) * (9/8)
A = 1 * (9 * 8)
A = 1 * 72
A = 72 cm²
b) A = (9/8x + x/2) * x - 1/2x * x
A = 13/8x² - 4/8x²
A = 9/8 * x²
A = 9/8 * 8 * 8
A = 9 * 8
A = 72 cm²
