Circle

Let S be the circle in the xy-plane defined by the equation x2+y2=4

Let E1E2 and F1F2 be the chord 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 a E3 the tangents of S at F1 and F2 meet at F3, and the tangents to S at G1 and G2 meet at G3.Then, the point E3,F3 and G3 lie on the curve