a) [tex] \frac{CM}{CB} = \frac{CN}{AC} \\ \frac{4}{8}= \frac{CN}{6} \\ \frac{1}{2}= \frac{CN}{6} \\ CN= \frac{6}{2} =3 \\ AN=AC-CN=6-3=3[/tex]
b) [tex] \frac{CN}{AC}= \frac{CM}{BC} \\ \frac{2}{6}= \frac{CM}{9} \\ CM= \frac{18}{6} =3 \\ BM=BC-CM=9-3=6 \\ NA=AC-CN=6-2=4 [/tex]
c) [tex]NC=12-9=3 \\ \frac{NC}{NA}= \frac{CM}{BM} \\ \frac{3}{9} = \frac{4}{BM} \\ BM= \frac{36}{3} \\ BM=12 \\ BC=BM+MC=12+4=16 [/tex]