# Definition Of Complementary Angles

## What are Complementary Angles?

**Complementary Angles**in geometry have the following characteristics. When two adjacent angles add up to 90° degrees they are called Complementary Angles. For an example, closely look at the picture below. We have a Right Angles

**∠DBC**which is a 90° angle. This 90° angle is cut in two by

**ray**

**BE**. So now the 90° is divided in to two smaller angles that add up to 90°. Now let us express this definition in geometric math terms.

- Another way to say angles are complementary is if two angles next to one another are Right Angles.
- Complementary angles have length but no width or height.
- If we look at the diagram below, the two adjacent angles
are
**∠DBE**and**∠EBC**. The sum of these two angles are 90° because they form a right angle. - Let us assume that angle
**∠DBE**is 65°. That means that 65° plus**∠EBC**equals 90°. Taken to the next step, 90° - 65° =**∠EBC**= 25°.