a.X=f(u)5*cos(u*10)*uY=g(u)15*(u*2+sin(u))Z=h(u)20<=u<=4piosa yb.X=f(u)sin(u)Y=g(u)cos(u)+uZ=h(u)u0<=u<=4piX=f(v)2*cos(v)Y=g(v)sin(v)Z=h(v)v0<=v<=6pi