4-3 Construct the velocity vector field along a constant motion around a circle

> x:=cos(t):

> y:=sin(t):

將圓上的每一點移動其切線斜率的`向量

> m:=[[x,y],[x+diff(x,t),y+diff(y,t)]];

> t:=n*2*Pi/100:

> plot([m$n=1..100],color=red,scaling=constrained,axes=none);

>