Measuring angles is not very complicated. The open side of the angle determines the angle’s size. The unit of measurement that is used for angles is called a degree. There are 360° in a circle, and an angle is a portion of that whole. Picture a circle divided into four equal parts. Each of those parts is comprised of a 90° (or right) angle.

In order to measure angles, it requires the right tool. The tool that is used for determining the size of an angle is called a protractor. A protractor is shaped like a half of a circle. It contains all of the degrees within a half circle, ranging from 0 to 180°. Lining up the angle using the protractor can prove the size of the angle.

Using a protractor begins with lining up the vertex of the angle with the center point of the protractor. A vertex is the point where the two sides of an angle meet. Once the vertex is in line with the center of the protractor, figuring out the degree of the angle is a simple as lining the angle up with the numbers running along the top of theprotractor.

If there is no protractor available, an estimate of the angle’s size can still be made. Knowing what sort of angle it is can help with that. As mentioned, a 90° angle is called a right angle. Any angle that is less than 90°, such as a 45 degree angle, is called an acute angle. If the angle is more than 90°, it is called an obtuse angle. The type of angle can be figured out at a glance and that can help determine an estimated size of the angle.

Angles are found all around our lives. An angle is created at every point where two lines come together to make a point. They are found in the corners of windows, cabinets and walls. Understanding angles, as well as how they work, is important, since they are important to important math techniques, for telling time and even building better cities and streets in our world. Here is a closer look at angles and information to help you easily identify a 45 degree angle and other types of angles found in everyday life.

## What is an Angle?

First, it is important to understand the definition of an angle. Simply defined, an angle is the space formed between two intersection lines near the point where the lines meet. Degrees are usually used to measure this space.

## Types of Angles

Multiple types of angles exist and understanding each type of angle and its definition is essential. The following are different types of angles and the information that makes them unique.

- Acute Angle – An acute angle is an angle measuring less than 90 degrees.
- Adjacent Angle – Angles that include a common side and common vertex are considered adjacent angles.
- Alternate Exterior – Alternate exterior angles are pairs of angles that are located on opposite sides of a transversal.
- Alternate Interior – When pairs of interior angles are located on opposite sides of the transversal, they are considered alternate interior angles.
- Complimentary Angle – Complimentary angles are two angles that form a right angle together, which means they must add up to 90 degrees. They are not required to be adjacent.
- Corresponding Angle – Pairs of angles that are located in similar positions are corresponding angles.
- Obtuse Angle – An obtuse angle must measure less than 180 degrees while measuring more than 90 degrees. Angles falling between 90-180 degrees are considered obtuse angles.
- Reflex Angle – Angles that measure larger than 180 degrees while measuring less than 360 degrees are considered reflex angles.
- Right Angle – The right angle measures exactly 90 degrees.
- Straight Angle – Straight angles appear like straight lines and measure exactly 180 degrees.
- Supplementary Angle – Any two angles that together measure 180 degrees are called supplementary angels.
- Vertical Angle – Vertical angles have sides formed by the same lines and a common vertex.

## Important Attributes of an Angle

To understand the different types of angles better, a few important attributes of an angle must be understood. The following are the important attributes of an angle that are important when describing them.

- Vertex – The point where two rays or lines are joined together is the vertex of the angle.
- Legs – The sides of the angle, referred to as legs, are the two lines that come together to make the angle.
- Interior – The space between the open “jaws” of an angle continues to extend into infinity and is called the interior of the angle.
- Exterior – The entire space on a plane that is not located on the interior of an angle is considered to be the exterior of an angle.

Once one understands the different types of angles and the important attributes of an angle, it becomes easier to identify a 45 degree angle. Since a 45 degree angle measures at less than 90 degrees where the legs of the angle come together, it is considered to be an acute angle. A better understanding of angles and how they work is important for geometry and other math principles and builds a good foundation for more complex math study. However, keep in mind that this information is also important for many everyday concepts as well.