Circumradius-inradius-side
Construct a triangle with circumradius R, inradius r, and a side a.
Hint:
Start with a circe of radius R and a chord of length a. Determine the opposite angle, say α. Observe that from the incenter, the side is seen at an angle (π + α)/2, and follow the construction in angle-altitude-side (https://www.geogebra.org/material/edit/id/mgwabaxj).