$ \vec{OA} $

O = Intersect(xAxis, yAxis)
A = (7, 4)
c = Circle(O, A)
u = Vector(O, A)
C = Point(u)
d = Circle(C, 1)
a = Ray(C, A)
D = Intersect(d, a)
v = Vector(C, D)
テキスト1: "点Aを動かして，ベクトルOA（" + (LaTeX[vec]) + "）の
単位ベクトル（赤いベクトル）を見てみよう．"