Question

如图 点C在线段AB上,AC=acm,BC=bcm,点M、N分别是AC、BC的中点

Answer 1

(1)

MN=MC+CN=AC/2 + BC/2=(AC+BC)/2=AB/2

(2)

MN=MC-NC=AC/2-BC/2=(AC-BC)/2=AB/2

(1)中的结论仍然成立

(3)

MN=AB/2