What are the key properties and characteristics of similar figures, and how can they be used to find missing lengths or angles?

Similar figures are figures that have the same shape but may differ in size. The key properties and characteristics of similar figures are as follows:

1. Corresponding angles: Corresponding angles in similar figures are congruent, which means they have the same measure. Corresponding angles are formed by a pair of corresponding sides.

2. Corresponding sides: In similar figures, corresponding sides are proportional. This means that the ratio of the lengths of corresponding sides is the same for all pairs of corresponding sides.

These properties can be used to find missing lengths or angles in similar figures. Here's how:

1. Finding missing lengths:
- Identify pairs of corresponding sides in the similar figures.
- Write a proportion using the lengths of corresponding sides.
- Solve the proportion to find the missing length. For example, if you have a proportion with the length of one side in the first figure over the length of the corresponding side in the second figure, you can cross-multiply and solve for the missing length.

2. Finding missing angles:
- Identify pairs of corresponding angles in the similar figures.
- Write an equation stating that the measures of corresponding angles are equal.
- Solve the equation to find the missing angle. This can be done by setting up an equation where the measure of one angle is equal to the measure of the corresponding angle.

Overall, the key to using the properties and characteristics of similar figures to find missing lengths or angles is to identify the corresponding parts between the figures and set up proportions or equations based on those correspondences.