> quadratrix:= plots[display]([sqr,quad(1)],scaling=constrained):

> pl0 := plot({[p(.6)],[[0,p(.6)[2]]],
[[0,p(.6)[2]/3]],[[p(.6+2/3*.4)[1],p(.6)[2]/3]]},style=point,symbol=circle,color=black):

> pl1 := plots[textplot]({[p(.6)[1]+.05,p(.6)[2],`P`],
[-.05,.4,`Q`], [-.05,.4/3,`R`], [.66,.2,`S`]}):

> seg3 := plot([[0,p(.6)[2]/3],[1,p(.6)[2]/3]],color=magenta,thickness=3):

> ang:=plot({[[0,0],[.63,0]],[[0,0],[p(.6)[1],p(.6)[2]]],
[[0,0], [p(.6+2/3*.4)[1],p(.6)[2]/3]]},color=blue,thickness=3):

> plots[display]([quadratrix,pl0,pl1,seg3,ang]);