Prove that the two circles shown below are similar. circle a is shown with a center at 3, 4 and a radius of 5. circle c is shown with a center of 0, negative 1 and a radius of 2.

All  circles are similar.

We can tell by placing their center at the same points and then telling the scale factor by the ratio of radius. R1 / R2 For instance, Lets say we had two circle and R1 had a radius of 4 and R2 had a radius of 2. If we put the smaller circle(the one with a radius of 2) center at the same center of the bigger circle, we would have a ratio 4/2 which mean we have a scale factor of 2. Also we could scale our smaller circle to be just like the circle with a radius of 4.