2435.sagews

u = var('u')
parametric_plot3d( (u/sqrt(2), u/sqrt(2), sin(u)), (u, 0, 20), plot_points=[1000], aspect_ratio=1)

u = var('u')
parametric_plot3d( (u, u^2, sin(u)), (u, 0, 200), plot_points=[1000])

x,y,t = var('x, y, t')
P1 = plot3d(sqrt(x^2+y^2),(x,-10,10),(y,-10,10))
P2 = plot3d(1+y,(x,-10,10),(y,-10,10), color="red")
P3 = parametric_plot3d([t,(t^2-1)/2,(t^2+1)/2],(t,-5,5), color="green", thickness=3)
show(P1+P2+P3, aspect_ratio=1)