Question

图中第七题输详细解答方式，谢谢

Answer 1

看图。

追问

费用小学的头脑算，哈哈

Answer 2

MN=CM+CN=0.5AC+0.5CB=0.5*(AC+CB)=0.5*AB=0.5*8=4

Answer 3

mc = 1/2 ac
cn = 1/2cb
mn=mc + cn = 1/2(ac + cb) = 4