var('t')
parametric_plot((cos(t),sin(t),t),(t,0,15),thickness=1)

var('t')
parametric_plot((cos(t),sin(t),t),(t,0,15),thickness=10 )

5+6

var('x,y')
plot(2*x^2, (x,-1,1))
plot3d(x^2 + y^2,(x,-1,1), (y,-1,1) )

var('x,y')
plot(2*x^2, (x,-5,5))
plot3d(x^2 + y^2, (x,-5,5), (y,-5,5), aspect_ratio=1 )

var('x,y')
plot(2*x^2, (x,-5,5))
plot3d(x^2 + y^2, (x,-5,5), (y,-5,5), aspect_ratio=(1,1,0.25) )