M mijloc AD, N mijlocAC⇒MN l.m.inΔ DAC, MN||DC,
MN=DC:2=8:2=4cm
Q mijlocBC, P mijlocBD⇒PQ l.m.ΔDBC, PQ||DC si =DC:2=4
PQ=4cm
M mijloc AD, Q mijlocBC⇒MQ l.m.in trapezul ABCD, MQ||DC||AB si
MQ=(8+12):2=20:2=10cm
MQ||DC
MN||DC
QP||DC⇒M,.N, P. Q coliniare⇒NP =MQ-MN-PQ=10-4-4=2cm
NP=2cm