α,β∈（0,π/2）cosα=2根号5/5 =2/根号5,sinα=根号[1-(2根号5/5)^2=1/根号5cosβ=根号10/10=1/根号10 ,sinβ=根号[1-(根号10/10)^2]=3/根号10osα/cosβ=(2根号5/5)/(根号10/10)=2根号＞1cosα＞cosβα＜βcos(...