Let S be the circle in the xy-plane defined by the equation x² + y² = 4.
Let S be the circle in the xy-plane defined by the equation x² + y² = 4. Let E₁E₂ and F₁F₂ be the chords of S passing through the point P₀(1, 1) and parallel to the x-axis and the y-axis, respectively. Let G₁G₂ be the chord of S passing through P₀ and having slope −1. Let the tangents to S at E₁ and E₂ meet at E₃, the tangents to S at F₁ and F₂ meet at F₃, and the tangents to S at G₁ and G₂ meet at G₃. Then, the points E₃, F₃, and G₃ lie on the curve