← etc / Encyclopedia of Triangle Centers

X₃₄₈₅¶

INTERSECTION OF LINES X₁X_4 AND X₇X_21

X₃₄₈₅ (INTERSECTION OF LINES X₁X_4 AND X₇X_21) constructed on acute reference triangle \((a, b, c) = (5, 6, 7)\) with unit baseline AB = \(1\).¶

"""GEOMETOR construction model for X_3485 = INTERSECTION OF LINES X_1X_4 AND X_7X_21."""

        from __future__ import annotations

        from pathlib import Path

        import sympy.geometry as spg
        from geometor.model import Model

        from geometor.etc.ops import (
            central_line,
            construct_baseline_triangle,
            create_model,
            eval_trilinear_point,
            gergonne_point_of,
            incenter_of,
            nagel_point_of,
            orthocenter_of,
            promote_point_to_top,
        )
        from geometor.etc.render import write_center_svg


        def construct_x_03485(
            model: Model, A: spg.Point, B: spg.Point, C: spg.Point
        ) -> spg.Point:
            """Construct X_3485 = INTERSECTION OF LINES X_1X_4 AND X_7X_21 on reference triangle ABC."""
            X_3485 = eval_trilinear_point(model, A, B, C, '(cos(A) + cos(B) + cos(C) + cos(B)*cos(C))', ID="X_3485", classes=["selected", "target"])
            X_1 = incenter_of(model, A, B, C, ID="X_1", classes=["center", "incident"])
            X_4 = orthocenter_of(model, A, B, C, ID="X_4", classes=["center", "incident"])
            central_line(model, X_1, X_4, 1, 4, incident=True)
            X_8 = nagel_point_of(model, A, B, C, ID="X_8", classes=["center", "incident"])
            X_12 = eval_trilinear_point(model, A, B, C, '1 + cos(B - C)', ID="X_12", classes=["center", "incident"])
            central_line(model, X_8, X_12, 8, 12, incident=True)
            X_7 = gergonne_point_of(model, A, B, C, ID="X_7", classes=["center", "incident"])
            X_21 = eval_trilinear_point(model, A, B, C, '1/(cos(B) + cos(C))', ID="X_21", classes=["center", "incident"])
            central_line(model, X_7, X_21, 7, 21, incident=True)
            return promote_point_to_top(model, X_3485)


        def build_model(
            sides: tuple[float, float, float] = (5.0, 6.0, 7.0),
            show_guides: bool = False,
        ) -> Model:
            """Build a `geometor.model.Model` for X_3485 on the given reference triangle."""
            model = create_model('X_3485 = INTERSECTION OF LINES X_1X_4 AND X_7X_21')
            A, B, C = construct_baseline_triangle(model, *sides, show_guides=show_guides)
            construct_x_03485(model, A, B, C)
            return model


        if __name__ == "__main__":
            here = Path(__file__).resolve().parent
            model_acute = build_model((5.0, 6.0, 7.0))
            model_acute.save(str(here / "x-03485.json"))
            write_center_svg(
                model_acute,
                here / "x-03485.svg",
                subtitle="(a, b, c) = (5, 6, 7) | AB = 1",
            )
        

X3485¶

X₃₄₈₅¶