Răspuns:
CD = 2cm, AB = 6cm.
Explicație pas cu pas:
In ordine, punctele sunt: A, C ,D ,B . Putem scrie AD = AC + CD ; CB = CD + DB
Stiind ca AC = 3 * BD => AC = 3 * DB
3 * DB + CD = AD
DB + CD = CB
3 * DB + CD = 5cm
DB + CD = 3cm
(3 * DB + CD) - (DB + CD) = 5 - 3cm = 2cm 2 * DB = 2cm DB = 1cm
AC = 3 * DB = 3cm
Cum CB = CD + DB, =>
CD = CB - DB = 3cm - 1cm = 2cm
Mai putem scrie ca AB = AC + CD + DB
AC = 3cm ; CD = 2cm; DB = 1cm;
AB = 3cm + 2cm + 1cm = 6cm.