Search Loci: Convergence:
Truth ... and if mine eyes
The Poetical Works of Charles Mackay. 1876.
Van Schooten's Ruler Constructions
Solution to Problem VI
Problem VI: To a given straight line AB and at a given point C in that line, to construct an angle given ACI equal to a given rectilineal angle E.
Construction: Construct above DE by the 4th problem, a perpendicular DF, meeting EF at F, and put at the point C in AB a line CG equal to ED, and from G construct over AB, by the preceding problem a perpendicular GH: I say that GI equals DF, and joining CI, the angle ACI will equal the angle E.