Question

已知向量a(-3,4),若|b向量|=1,b向量⊥a向量,则向量b=

Answer 1

let b = (x,y)

x^2+y^2 =1 (1)

a.b=0

-3x+4y=0 (2)

sub (2) into (1)

x^2 + (3x/4)^2 =1

25x^2/16 =1

x= 4/5 or -4/5

x= 4/5 ,y= 3/5

x= -4/5 ,y= -3/5

b = (4/5,3/5) or (-4/5,-3/5)