Construct various crosssections of a cone.  

When a cube is rotated about its main diagonal,
describe
the region wiped out. 
Construct onehalf of the tangent cone of a sphere. 
Construct a surface which appears as a triangle along the
xaxis, 
appears as a triangle along the yaxis,

apprears as an astroid along the zaxis 
Construct this pattern form by line segments joining [cos(t),0]
with [0,sin(t)] as t ranges over the interval [0,2p]. ¡@ m:=[[cos(t),0],[0,sin(t)]]; 
Construct this pattern: t:=Pi*n/100:x:=cos(t)1:y:=sin(t): 