Question

已知与a共线的单位向量b=(-√3/2,1/2)如果a的起点坐标为（1,-2)模为4√3,则a的终点坐标为

Answer 1

|a| = 4√3

b = (-√3/2,1/2)

a = |a|b

= 4√3 (-√3/2,1/2))

= (-6,2√3)

let a 的终点坐标 = (x,y)

(x,y) - (1,-2) =a

(x-1,y+2) = (-6,2√3)

x = -5,y=2√3-2

a 的终点坐标 = (x,y) = (-5,2√3-2)