Répondre :
Aire(MBCD) = (MB + CD) x AD / 2
= (2AB - AM) x AD / 2
= (24 - AM) x 3
= 72 - 3AM
Aire(ADM) = AM x AD / 2
= 3AM
on sait que:
Aire(MBCD) - Aire(ADM) = 15
72 - 3AM - 3AM = 15
72 - 6AM = 15
6AM = 72 - 15
6AM = 57
AM = 57 / 6
AM = 9.5 cm
= (2AB - AM) x AD / 2
= (24 - AM) x 3
= 72 - 3AM
Aire(ADM) = AM x AD / 2
= 3AM
on sait que:
Aire(MBCD) - Aire(ADM) = 15
72 - 3AM - 3AM = 15
72 - 6AM = 15
6AM = 72 - 15
6AM = 57
AM = 57 / 6
AM = 9.5 cm