0 sides of two or more polygons that are matched so they can be compared
1 sides of two or more polygons (= flat shapes) that are matched so they can be compared
However, proportionality of corresponding sides is not by itself sufficient to prove similarity for polygons beyond triangles (otherwise, for example, all rhombi would be similar).
The lengths of these lines, as well as the lengths of the segments between the point and the corresponding sides, are measured individually.
The altitudes of similar triangles are in the same ratio as corresponding sides.
The corresponding sides of similar triangles have lengths that are in the same proportion, and this property is also sufficient to establish similarity.
It can be shown that two triangles having congruent angles ("equiangular triangles") are similar, that is, the corresponding sides can be proved to be proportional.
The pairs of sides are then known as corresponding sides.
An image showing the corresponding sides can be found online;.
For example, the "sine", "cosine", and "tangent" ratios in a right triangle can be remembered by representing them and their corresponding sides as strings of letters.
