Enter any single angle of the angles between parallel lines into the calculator to determine the missing three angles.

- Complementary Angle Calculator
- Interior Angle Calculator
- Central Angle Calculator
- Angle Addition Calculator

## Vertical Angle Formula

The following formula is used to calculate vertical angle pairs.

A=C , B=D

A= abs (b-180)

- Where A,B,C,and D are the vertical angles described in the diagram below.

## Vertical Angle Definition

**What are vertical angles? **Vertical angles are two opposite angles created by intersecting lines. In the diagram above, A and C are vertical angles and B and D are vertical angles. Vertical angles are always equal to one another. (A=C).

## Example

How to calculate vertical angles?

**First, determine one given angle.**First, this example, an angle A is given as 30 degrees.

**Using the formula above, determine the rest of the angles.**Since C is equal to A, C = 30 degrees. B = abs (30-180) = 150. Since D is equal to B then D = 150. The final answer is A=30, C=30, B=150, D=150

## Vertical Angles

**Are vertical angles congruent? **By definition, vertical angles are considered congruent angles, since the only requirement of congruent angles is that they are equal. This is the same as the definition for vertical angles.

**Are vertical angle supplementary? **A pair of vertical angles does not have to be supplementary, although they can be if they are equal to 90 degrees each.

**Are vertical angles complementary? **Vertical angles are only complementary when they are equal to 45 degrees, however, the sum of a vertical angle and the other vertical angle of two intersecting lines is always complementary.