填空题 设x=rcost+3t,y=rsint+3,分别令r=2,3,4,画出参数t=0~10区间生成的x~y曲线. >> t=linspace(0,10); >> r1=_________; >> x1=(r1*________+3*t); >> y1=r1*sin(t)+3; >> r2=3; >> x2=(r2*cos(t)+3*t); >> y2=r2*sin(t)+3; >> r3=4; >> x3=(r3*cos(t)+3*t); >> y3=r3*sin(t)+3; >> plot(________,y1,'r',x2,y2,'b',x3,____________,'m')