x1:=t->4*cos(t):y1:=t->2*sin(t):
x2:=t->1.4*cos(t)-1:y2:=t->1.2*sin(t):
x3:=t->cos(t)+2:y3:=t->sin(t)/2:
Quxian1:= plot([x1(t),y1(t),t=0..2*Pi],color=gray,filled=true):
Quxian2:= plot([x2(t),y2(t),t=0..2*Pi],color=white,filled=true):
Quxian3:= plot([x3(t),y3(t),t=0..2*Pi],color=white,filled=true):
K:=50:
for i from 1 to K do
ti:=i*2.5*Pi/K:
quxian1[i]:=plot([x1(t),y1(t),t=0..ti],thickness=4):
quxian2[i]:=plot([x2(-t),y2(-t),t=0..ti],thickness=4):
quxian3[i]:=plot([x3(-t),y3(-t),t=0..ti],thickness=4):od:
quxian1:=display(seq(quxian1[i],i=1..K),insequence=true):
quxian2:=display(seq(quxian2[i],i=1..K),insequence=true):
quxian3:=display(seq(quxian3[i],i=1..K),insequence=true):
display(quxian3,quxian2,quxian1,Quxian3,Quxian2,Quxian1,scaling=constrained);
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