Scale drawings are based on the geometric principle of similarity. Two figures are similar if they have the same shape even though they may have different sizes. Any figure is similar to itself, so, in this specific case, the similar figures do actually have the same size as well as the same shape.

Scale Drawing and Models in Geometry

In traditional Euclidean geometry, two polygons are similar if their corresponding angles are equal and their corresponding sides are in proportion. For example, the two right triangles shown below are similar, because the length of each side in the large triangle is twice the length of the corresponding side in the small triangle.

In transformational geometry, two figures are said to be similar if one of them can be "mapped" onto the other one by a transformation that expands or contracts all dimensions...