a)MB=AB-AM=12-5=7
MN II BC rez din TTh ca MB/AB=NC/AC 7/12=4/AC AC=12*4/7=48/7
si AN=AC-NC=48/7-4=48/7-28/7=20/7
B)MN II BC rez din TTh ca MB/AB=NC/AC 6/AB=12/28 AB=6*28/12=14
AM=AB-MB=14-6=8
C)MN II BC rez din TTh ca AM/AB=AN/AC 3/5,4=AN/7,2 AN=3*7,2/5,4=21,6/5,4=4
NC=AC-AN=7,2-4=3,2