What makes two figures similar?

For two figures to be similar, they must be the same shape, not necessarily the same size. They must also follow theses two rules: 1., They must have the same exact angles in the same places, and 2., their sides must grow in proportion. That means that when one figure is bigger than the other, it can't be taller but super skinny, or taller but super wide. Think of when your mom or dad buys your school photos. There is the wallet size, and then you've got your huge poster size. The people who take and adjust the pictures have to make sure that when they grow or shrink the pictures, they don't end up looking like your reflection in the fun house mirror. Each side must grow or shrink at the same rate. For example, a triangle with side 1 being 2 inches long, side 2 being 3, and side 3 being 4 inches long. The similar figure (has to be another triangle) could be 4 inches long for side 1, 6 inches long for side 2, and 8 inches long for side 3. It would be twice as big. You see what I mean? So for two figures to be similar, they must be the same shape, have the same angles, and grow in proportion. P.S. in case your wondering, congruent figures are automatically similar- times one!