Angle notation is the way of naming them to know which angle we are referring to. When reading the data, it is customary to mark the given angles and the angle that needs to be found. In this way, we can obtain a better visual image that allows us to find the solution in the most efficient way possible. When we want to demonstrate something or express the angles verbally, we must designate them in a correct and clear manner. Besides, correct notation is important and indispensable to avoid errors.

We can name the angle with the letter that defines its vertex.

Notation for angles

2. We can name the angle with the letters with which we denote the segments that form the angle, ensuring that the letter corresponding to the vertex is in the middle.

3. We can also name the angle using the vertex letter accompanied by numerical subscripts.

4. Likewise, we can name the angle using Greek letters.

Remember! The main symbol is:

If you are interested in learning more about other angle topics, you can enter one of the following articles:

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Before almost all notations, we will draw the main symbol. Next comes the name of the angle. We will start with the notation forms:

The first way of angle notation

We can name the angle with the letter that defines its vertex. Simply observe which vertex the angle belongs to and write its name next to the main symbol. When we want to refer to the marked angle, we will indicate it in the following way:

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We can name the angle with the letters with which we denote the segments that form the angle, ensuring that the letter corresponding to the vertex is in the middle. What does this mean? In this example, the indicated angle is formed by the segments $AC$ and $AB$, having its vertex at the point $A$. Therefore, we can name it in the following way:

As long as the vertex is in the middle of the notation, it will be correct. You might be wondering why bother and note the three letters? The answer is quite simple. In certain cases, we will encounter angles that share a vertex and, to distinguish them, we must use the three-letter notation. How will we distinguish between the pink angle and the green angle? We will be forced to use the three-letter notation, ensuring that the vertex always remains in the middle.

The notation for the pink angle will be: $∢ EBA = ∢ABE$ The notation for the green angle will be: $∢ CBE = ∢EBC$

The third way of angle notation

To name angles we can use numbers. The angle notation will include the name of its vertex and the number noted inside the angle written as a subscript. Let's see it in the following example:

The notation for the pink angle will be: $∢A_1$ The notation for the green angle will be: $∢A_2$

We can also denote the angle using Greek letters. Examples of Greek letters:

And we will call them: alpha, beta, and gamma.

The notation for the pink angle will be: $∢α$ The notation for the green angle will be: $∢β$

Now you can name an angle in four different ways!

No matter which way you choose to denote angles, all are equally correct. Find out if a specific way is required for notation and if not, simply use the one that is most comfortable for you.

We are looking for an answer where the letter B, which represents the angle in the drawing, is in the middle.

Therefore, answer A is correct since the letter B is in the middle:

$ABC$

Answer

$∢\text{ABC}$

Exercise #2

Name the angle of the figure:

Video Solution

Step-by-Step Solution

We are looking for an answer where the letter D, which represents the angle in the drawing, is in the middle.

Therefore, answer B is correct since the letter D is in the middle:

$BDK$

Answer

$∢\text{BDK}$

Exercise #3

In which of the figures is the angle EBCmarked?

Video Solution

Step-by-Step Solution

We will look for the diagram where the colored angle is angle B since it is the middle one. We can see that in answer A, angle B is the colored one, and therefore this is the correct answer.

Answer

Exercise #4

Is it possible to mark all angles with a single letter?

Video Solution

Step-by-Step Solution

This is not possible owing to the fact that the two angles that are divided within angle BAD are: