# Aa Criterion in Triangles: Everything You Need to Know

In geometry, there are a lot of different theorems and postulates that govern all of the shapes. These theorems make up the foundation for everything else that will be learned in geometry. One such theorem is the aa criterion. This theorem states that two angles are congruent if and only if their corresponding sides are proportional. In other words, this theorem is a way to determine whether two angles are equal by looking at the ratio of their sides. Keep reading to learn more about the aa criterion and how to use it!

## How to Use the Aa Criterion

There are a few steps that need to be followed in order to use the aa criterion correctly. First, you need to identify which sides of the triangle correspond to each other. Second, you need to set up a proportion using these corresponding sides. The last step is to solve for x and determine whether or not the two angles are indeed equal.

Let’s look at an example so that this process becomes clearer. Say we have a triangle ABC and we want to know if angle A is equal to angle C. We would first need to identify which sides of the triangle correspond to each other. In this case, side AB corresponds to side AC because they are both opposite angles C. Next, we would set up a proportion using these corresponding sides. It would look like this: AB/AC=A/C. Lastly, we solve for x and determine whether or not the two angles are equal. In this proportion, x would be angle A since we are solving for it. If angle A is equal to angle C, then the two angles are indeed congruent!

## Conclusion:

The aa criterion is just one way out of many ways to determine whether or not two angles in a triangle are congruent. However, it is definitely one of the easier ways once you get some practice with it! Just remember the steps: identify which sides correspond with each other, set up a proportion using these corresponding sides, and solve for x. With some practice, using the aa criterion will be second nature!

## FAQ

### What is AA criterion?

The aa criterion is a theorem that states two angles are congruent if and only if their corresponding sides are proportional.

### What does AA mean in triangles?

AA means that the two angles are congruent, or equal.

### What is the AA theorem in geometry?

The AA theorem is a way to determine whether two angles are equal by looking at the ratio of their sides.

### Why is the AA criterion enough to prove that two triangles are similar?

The AA criterion is enough to prove that two triangles are similar because if the two angles are equal, then the corresponding sides must be proportional. This means that the triangles must have the same shape, just possibly different sizes. Therefore, the triangles are similar.