Understanding the concept of vertical angles and the angles’ relationship gives you a chance to learn how to find unknown angle measures and relate pairs of angles. Get ready and learn how to spot vertical angles easily!

## What Are Vertical Angles?

Vertical angles are **angles facing opposite each other at a point where two lines cross each other**. When two lines intersect, four angles are formed. Each pair meets at the vertex. This is why each pair of angles are called vertical angles, from the word, **vertex**.

Take a look at the pair of angles, *m°* and *n°*, formed by two intersecting lines. These two meet at the vertex, *O*, and are facing opposite each other. Hence, the two angles are a pair of vertical angles.

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When it comes to vertical angles, always remember: **vertical angles are equal**. This means that the pair of angles, *m°* and *n°*, have equal angle measures.

Can you identify two pairs of angles just by looking at the figure above? Focus on the angles that face opposite each other:

**First pair of vertical angles:***∠AOC*and*∠BOD*face opposite each other.**Second pair of vertical angles:***∠AOB*and*∠COD*meet at the vertex*O*.

As you can see from the figure, each pair of angles will have equal angle measures.

Don’t forget this golden rule for vertical angles: their measures are equal. Use this to answer the sample problem below!

#### Example 1

Using the figure shown below, what is the value of x?

The two angles, *64°* and *x°*, face opposite each other between two intersecting lines. Hence, these two are vertical angles. Applying the golden rule for vertical angles, their angle measures must be equal.

64° = *x*°

*x* = 64

Hence, *x* is equal to 64.