bonjour,
voir schéma joint,
on admet que (BC) et (CD) sont ⊥ (AD)
triangle rectangle BEA :
A = AE*BE/2
AE = AD-BC = 55-40 = 15
A = (15*20)/2 =150m²
trapeze rectangle EBCD
A = [(BE+CD)*ED]/2
= [(20+50)*40]/2
= 1400m²
A terrain = 1550m²
30g (30*1550 =46500g = 46,5kg)
1m² 1550m²