Make nine rays with the center of the circle as the vertex, and pass through two circles at points (A 1, B 1), (A2, B2) ... (A9, B9)(A is a small circle, B is a big circle, and the subscripts on the same ray are the same). Then there are four color combinations: (red) (red) let nature take its course (A 1, B 1) (A2, B2) (A3, B3), then triangles A 1A2A3 and B 1B2B3 are similar triangles that meet the requirements.