A____Q_P__M___N__B_______C,
∵M为AB中点,∴AM=1/2AB,
∵N为AC中点,∴AN=1/2AC,
∴MN=AN-AM=1/2(AC-AB),
∵P为NA中点,∴AP=1/2NA=1/4AC,
∵Q为MA中点,∴AQ=1/2AM=1/4AB,
∴PQ=AP-AQ=1/4(AC-AB),
∴MN:PQ=2.
精心打造,解题不易,
A____Q_P__M___N__B_______C,
∵M为AB中点,∴AM=1/2AB,
∵N为AC中点,∴AN=1/2AC,
∴MN=AN-AM=1/2(AC-AB),
∵P为NA中点,∴AP=1/2NA=1/4AC,
∵Q为MA中点,∴AQ=1/2AM=1/4AB,
∴PQ=AP-AQ=1/4(AC-AB),
∴MN:PQ=2.
精心打造,解题不易,