Question

线段AB=6cm,在直线AB上畵线段BC=4cm,若M,N分别是AB,BC的中点

Answer 1

1.C在AB之间时,MN=BM-BN=AB/2-BC/2=(AB-BC)/2=(6-4)/2=1cm

C在AB之外时,MN=MB+BN=AB/2+BC/2=(AB+BC)/2=(6+4)/2=5cm

2.C在AB之间时,MN=BM-BN=AB/2-BC/2=(AB-BC)/2=(a-b)/2

C在AB之外时,MN=MB+BN=AB/2+BC/2=(AB+BC)/2=(a+b)/2

3.C在AB之间时,MN=(AB-BC)/2

C在AB之外时,MN=(AB+BC)/2