a⊥b则a*b＝0
|a-b|^2＝(a-b)*(a-b)＝|a|^2+|b|^2＝5+1＝6|a-b|＝√6
|a+tb|^2＝(a+tb)*(a+tb)＝|a|^2+t^2×|b|^2＝5+t^2|a+tb|＝√(5+t^2)
(a-b)*m＝(a-b)*(a+tb)＝|a|^2-t|b|^2＝5-t
a-b与m夹角π/4则cos(π/4)＝[(a-b)*(a+tb)]/|a-b|*|a+tb|]＝(5-t)/[√6*(5+t^2)t＝(-5±3√5)/2|a-b|^2＝(a-b)*(a-b)＝|a|^2+|b|^2＝5+1＝6|a-b|＝√6,|a-b|^2不应该=a²-2ab+b²吗a*b=0,因为a⊥b则a*b＝0