restart;

a:=3;

c:=7;

z:=a*sin(t);

r:=c+a*cos(t);

x:=r*cos(s);

y:=r*sin(s);

plot3d([x,y,z],s=0..2*Pi,t=0..2*Pi,

restart;

a:=3;

c:=7;

z:=a*sin(t);

r:=c+a*cos(t);

x:=r*cos(s);

y:=r*sin(s);

plot3d([x,y,z],s=0..2*Pi,

restart;

a:=3;

c:=7;

z:=a*sin(t);

r:=c+a*cos(t);

x:=r*cos(s);

y:=r*sin(s);

plot3d([x,y,z],s=0..Pi,

restart;

a:=1;b:=2;c:=sqrt(a^2+b^2);

t:=3*s;

z:=a*sin(t);

r:=c+a*cos(t);

x:=r*cos(s+h);

y:=r*sin(s+h);

plot3d([x,y,z],s=0..2*Pi,h=0..Pi/3,

restart;

a:=1;b:=2;c:=sqrt(a^2+b^2);

t:=3*s;

z:=a*sin(t);

r:=c+a*cos(t);

x:=r*cos(s+h);

y:=r*sin(s+h);

p1:=plot3d([x,y,z],s=0..2*Pi,h=0..Pi/3,

scaling=constrained,grid=[41,15],color=red):

p2:=plot3d([x,y,z],s=0..2*Pi,h=Pi/3..2*Pi/3,

scaling=constrained,grid=[41,15],color=green):

with(plots):

p:=display(p1,p2):

restart;

c:=2;

a:=1;

b:=sqrt(c^2-a^2);

z:=a*sin(t);

r:=c+a*cos(t);

x:=r*cos(s);

y:=r*sin(s);

w:=solve(z=a/b*x,s);

p:=plot3d([x,y,z],t=0..2*Pi,s=-w..w,

scaling=constrained,grid=[17,21]):

restart;

with(plots):

a:=1;

b:=2;

c:=sqrt(a^2+b^2);

z:=a*sin(t);

r:=c+a*cos(t);

x:=r*cos(s);

y:=r*sin(s);

p1:=plot3d([x,y,z],s=0..2*Pi,t=0..2*Pi,

scaling=constrained,style=patchnogrid):

with(plots):

p2:=spacecurve([b*cos(t),a+c*sin(t),a*cos(t)],

t=0..2*Pi,thickness=5,scaling=

constrained,color=black):

restart;

a:=1;b:=2;c:=sqrt(a^2+b^2);

x1:=b*cos(t);

y1:=a+c*sin(t);

z:=a*cos(t);

x:=cos(s)*x1-sin(s)*y1;

y:=sin(s)*x1+cos(s)*y1;

plot3d([x,y,z],s=0..Pi,t=0..2*Pi,

restart;

a:=1;b:=2;c:=sqrt(a^2+b^2);p:=2*Pi/3;

s:=3*t;

z1:=a*sin(t);

r1:=c+a*cos(t);

x1:=r1*cos(s);

y1:=r1*sin(s);

z2:=a*sin(t+p);

r2:=c+a*cos(t+p);

x2:=r2*cos(s);

y2:=r2*sin(s);

w:=expand((1-u)*[x1,y1,z1]+u*[x2,y2,z2]);

plot3d(w,u=0..1,t=0..2*Pi,scaling=