Suppose x is any positive number. Circle 1: center (5,4) and a radius of 5x Circle 2: center (5,4) and a radius of 2x Why is circle 1 similar to circle 2? Circle 1 is a dilation of a circle with a scale factor of 2.5. Circle 1 is congruent to circle 2. Circle 1 is a dilation of circle 2 with a scale factor of 0.4. Circle 1 and circle 2 have the same radius.​