If two angles in one triangle are congruent to two angles in another triangle, then the two triangles are similar.
Congruent figures are identical in size, shape and measure.
Indirect measurement is the process of using the characteristics of similar triangles to measure distances.
A proportion is an equation that shows two equivalent ratios.
Proportional reasoning involves deducing the relationship between the numerators or the denominators of a proportion. Anytime you have a proportion, there is some kind of relationship between the values.
Two figures are similar if they have the same shape, but not necessarily the same size.
Learn to recognize similarity and use similar figures with indirect measurement.