← etc / Encyclopedia of Triangle Centers

X₃₇₈¶

REFLECTION OF X₂₂ IN X₃

X₃₇₈ is the reflection of X₂₂ in X₃.

X₃₇₈ (REFLECTION OF X₂₂ IN X₃) constructed on acute reference triangle \((a, b, c) = (5, 6, 7)\) with unit baseline AB = \(1\).¶

"""GEOMETOR construction model for X_378 = REFLECTION OF X_22 IN X_3."""

        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,
            centroid_of,
            circumcenter_of,
            construct_baseline_triangle,
            create_model,
            eval_trilinear_point,
            promote_point_to_top,
        )
        from geometor.etc.render import write_center_svg


        def construct_x_00378(
            model: Model, A: spg.Point, B: spg.Point, C: spg.Point
        ) -> spg.Point:
            """Construct X_378 = REFLECTION OF X_22 IN X_3 on reference triangle ABC."""
            X_378 = eval_trilinear_point(model, A, B, C, 'sec(A) + 2*cos(A)', ID="X_378", classes=["selected", "target"])
            X_2 = centroid_of(model, A, B, C, ID="X_2", classes=["center"])
            X_3 = circumcenter_of(model, A, B, C, ID="X_3", classes=["center"])
            central_line(model, X_2, X_3, 2, 3)
            X_33 = eval_trilinear_point(model, A, B, C, '1 + sec(A)', ID="X_33", classes=["center", "incident"])
            X_36 = eval_trilinear_point(model, A, B, C, '1 - 2*cos(A)', ID="X_36", classes=["center", "incident"])
            central_line(model, X_33, X_36, 33, 36, incident=True)
            X_34 = eval_trilinear_point(model, A, B, C, '1 - sec(A)', ID="X_34", classes=["center", "incident"])
            X_35 = eval_trilinear_point(model, A, B, C, '1 + 2*cos(A)', ID="X_35", classes=["center", "incident"])
            central_line(model, X_34, X_35, 34, 35, incident=True)
            return promote_point_to_top(model, X_378)


        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_378 on the given reference triangle."""
            model = create_model('X_378 = REFLECTION OF X_22 IN X_3')
            A, B, C = construct_baseline_triangle(model, *sides, show_guides=show_guides)
            construct_x_00378(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-00378.json"))
            write_center_svg(
                model_acute,
                here / "x-00378.svg",
                subtitle="(a, b, c) = (5, 6, 7) | AB = 1",
            )
        

X378¶

X₃₇₈¶