cho đoạn thẳng AB va trung diem M cua no
a) CMR:Neu C la diem thuoc tia doi cua tia BA thi CM= \(\frac{CA+CB}{2}\)
b)CMR:neu C la diem nam giua hai diem M va B thi CM= \(\frac{CA-CB}{2}\)
K
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6 tháng 3 2016
Vì M là trung điểm của AC
=>CM=1/2AC
Vì N là trung điểm của BC
=>CN=1/2BC
Ta có:
MN=MC+CN=1/2AC+1/2BC=1/2(AC+BC)=1/2.16=8(cm)
S
14 tháng 11 2018
MIk cũng ko thể hiểu nổi đề nếu đúng đoạn là đoạn thẳng à
A___________M_________________________C______________________B
Ta có:
AB=AC+CB=8cm
Mà AC-BC=2cm
=> 2 BC=8cm-2cm=6cm
=> BC=6cm:2=3cm
AC=8cm-3cm=5cm
Vì C là trung điểm của BM
=>CB=CM=1/2 BM
=> BM=3cm.2=6cm
=> AM=8cm-6cm=2cm
