P为线段AC的中点,M为线段AB的中点,N为线段BC的中点.MN=PC,MP=AP-PB的差除以二,为什么对,急

回答MP=AP-AM=1/2(AC-AB)
CN=1/2BC=1/2(CA-CB)
即MP=CN
即MP+PB+BN=PB+BN+CN
即MN=PC
2 MP=1/2(AC-AB)
=1/2AC-1/2AB
=AP-AM
=AP-1/2AB
=AP-1/2(AP+PB)
=AP-1/2AP-1/2BP
=1/2AP-1/2BP
=1/2(AP-PB)原来是这样，再问一下PN=1/2(PC＋PB）呢？解PN=PB+BN=PB+NC=PB+1/2BC=1/2PB+1/2PB+1/2BC=1/2PB+1/2(PB+BC0=1/2PB+1/2PC=1/2(PC+PB)不懂请问，谢谢采纳。