What is the surface area of the pyramid?

They are similar because the radius of circle x is a multiple of circle y. proof: translate smaller circle y to the location of circle x  so that they are concentric (same center location (2, the translation would be moving the center of y left 2 units and up 6 units. now that the centers are concentric a dilation is need to increase the size of circle y to coincide with circle x. dilation by the scale factor, k k = 6/3 k = 2 as you can see the scale factor, k is a ratio of the radius thus proving the circles are similar