bonjour
a) 3.5 x 2.8 = 9.8
aire = 9.8 dm ²
P = 2 ( 3.5 + 2.8 ) 12.6 dm
b ) 7.4 x 2.1 = 15.54 cm²
P = 2 ( 7.4 + 2.1) = 19 cm
c) largeur = 360 : 20 = 18 cm
P = 2 ( 18 + 20 ) = 76 cm
d) largeur = [ 45 - ( 2 x 7.2 ) ] /2 = ( 45 - 14.4 ) / 2 = 15.3 m
Aire = 7.2 x 15.3 = 110.16 m²