G.100 diameter bisects chord iff perpendicular — Code

III.3

A segment through the center of a circle bisects a chord not through the center if and only if it cuts the chord at right angles.
C D A B F E
"""Programmatic construction for Book III, Proposition 3 (III.3)."""

        from __future__ import annotations

        from geometor.model import Model


        def construct_g1() -> Model:
            """Construct the figure 0016.g1 using geometor.model."""
            model = Model("III.3")

            # Points (y-inverted for standard mathematical coordinates)
            E = model.set_point(93, -104, ID="E")
            C = model.set_point(93, -28, classes=["given"], ID="C")
            D = model.set_point(93, -180, classes=["given"], ID="D")
            F = model.set_point(93, -140, ID="F")
            A = model.set_point(26.07, -140, classes=["given"], ID="A")
            B = model.set_point(159.93, -140, classes=["given"], ID="B")

            # Construction circle ABC
            model.construct_circle(E, C)

            # Segments
            model.set_segment(C, D)
            model.set_segment(A, B)
            model.set_segment(E, A)
            model.set_segment(E, B)
            model.set_segment(A, F)
            model.set_segment(F, B)
            model.set_segment(F, E)
            model.set_segment(C, E)
            model.set_segment(E, D)
            model.set_segment(C, F)
            model.set_segment(F, D)

            # Sections
            model.set_section([A, F, B])
            model.set_section([C, E, D])
            model.set_section([C, F, D])

            # Polygons
            model.set_polygon([E, A, F])
            model.set_polygon([E, B, F])
            model.set_polygon([E, A, B])

            # Angles (wedges)
            model.set_wedge(F, A, A, E)
            model.set_wedge(F, E, E, B)
            model.set_wedge(A, E, E, F)
            model.set_wedge(B, F, F, E)

            return model


        if __name__ == "__main__":
            construct_g1()