?表示有N种方法?表示用UG3.0可以实现?双外摆线b=2.5l=2.5t=1xt=3bcos(t360)lcos(3t360)yt=3bsin(t360)lsin(3t360)?星形线a=5t=1xt=a(cos(360t))3yt=a(sin(360t))3叶形线a=10t=1xt=3at(1(t3))yt=3a(t2)(1(t3))?螺纹线t=1xt=4cos(t(5360))yt=4