Question

Answer 1

Xét ΔABC có AM/MB=AN/NC

nên MN//BC

Xét ΔABC có CN/NA=CP/BP

nên NP//AB

Answer 2

Xét tam giác ABC có : 

\(\dfrac{AM}{MB}=\dfrac{AN}{NC}=\dfrac{3}{6}=\dfrac{4}{8}=\dfrac{1}{2}\)

=> MN // BC ( Ta lét đảo ) 

\(\dfrac{CN}{NA}=\dfrac{CP}{BP}=\dfrac{8}{4}=\dfrac{10}{5}=2\)

=> NP // AB ( Ta lét đảo )

Answer 3

Xét \(\Delta ABC\) có:

\(\dfrac{AM}{MB}=\dfrac{3}{6}=\dfrac{1}{2}\)

\(\dfrac{AN}{NC}=\dfrac{4}{8}=\dfrac{1}{2}\)

\(\Rightarrow\dfrac{AM}{MB}=\dfrac{AN}{NC}\)

\(\Leftrightarrow MN//CB\)

Xét \(\Delta ABC\) có:

\(\dfrac{AN}{NC}=\dfrac{4}{8}=\dfrac{1}{2}\)

\(\dfrac{BP}{PC}=\dfrac{5}{10}=\dfrac{1}{2}\)

\(\Rightarrow\dfrac{AN}{NC}=\dfrac{BP}{PC}\)

\(\Leftrightarrow NP//AB\)