Mathematically similar similar when they have a true proportion. You can find out of 2 figures are similar using ratio. To do this you find out the ratio of the 2 figures and cross multiply them. If the 2 answers you get are the same you know that they are similar. You can also find out if figures are similar using scale factor. A scale factor is a number that you can use to multiply the sides of a figure to get the corresponding side of a similar figure. Another way to tell if figures are similar is seeing if they have a similar shape and the corresponding angles have to be congruent.

True or False any 2 rectangles are similar? The answer is FALSE. Not all rectangles share a scale factor. An example is that one rectangle could be 7 by 10 and another could be 3 by 4. There is no scale factor between these two rectangle which means that they are not similar. Though all rectangles share angles and same general shape it does not mean they are similar.

True or False any two equilateral triangles are similar? The answer is TRUE. All of the angle are 60 degrees so that works, all of the sides are the same size so that works and because all of this the ratio of the corresponding sides will be the same.