Question

若向量a=（3,m）的单位向量为（1,0）,则m=

Answer 1

a/|a|=(1,0)

(3,m)/(9+m^2)^(1/2) = (1,0)

=>

3/(9+m^2)^(1/2) = 1 and m/(9+m^2)^(1/2) =0

=> 9+m^2=9 and m=0

=> m=0