Types of Angles

The concept of angles plays a crucial role in mathematics and geometry. It forms the basis of various calculations and real-world applications. Understanding angles and types of angles helps with problem-solving and practical applications like construction, design, and even something as basic as telling time. This study guide will explore types of angles with types of angles definitions, types of angles examples, and types of angles explanations in an in-depth manner for comprehensive understanding.

1.0What Are Angles?

The word angle was derived from the Latin word "Angulus,” which means corner. Angles are geometric figures formed by two rays/lines that share a common endpoint, called Vertex. Angles are usually measured in degrees (°) using a protractor. The symbol of angle is ∠. 

2.0Mathematics: Types of Angles

In mathematics, types of angles are classified based on their degree measures. Here is a breakdown of different types of angles in geometry with diagrams for better understanding.

• Acute Angle

An acute angle is an angle that measures less than a right angle or 90°. So, that would include any angle from 0° up to 89°. For example, 30°, 45°, and 60° are all acute angles. It is found in various real-life structures like rooftops and the hands of a clock at 10:10.

• Right Angle

A right angle is made by two lines or rays that form an angle of 90° at the vertex. That means both the lines or the rays are perpendicular to each other. A corner of a square or a rectangle typically forms a right angle. 

• Obtuse Angle

Obtuse angles are a type of angle that is greater than 90° and less than 180°. For example, 96°, 175°, 160°, and so on are all obtuse angles. These are bigger than an acute angle and smaller than a straight line.

• Straight Angle

A straight angle refers to an angle that is equal to an angle of 180°. It is called a straight angle as it appears like a straight line.

• Reflex Angle

A reflex angle always measures greater than 180° but is less than 360°. It extends beyond a straight angle, but it does not complete a full circle.

• Complete Angle

A complete angle is a type of angle that measures exactly 360°. It represents a complete turn or a full rotation and thus forms a circle around a point. 

3.0Types of Angles in Parallel Lines

When a set of parallel lines is cut by a transversal, it forms a pair of angles. Understanding the types of angles in parallel lines is crucial in geometry and real-world applications. Let’s look at the types of angles with definition formed by parallel lines for better understanding.

• Corresponding Angles

Corresponding Angles are angles that are formed at the corresponding corners when two parallel lines are intersected by a transversal. These angles are equal.

• Alternate Interior Angles

Alternate interior angles are always formed on opposite sides of the transversal and at the interior of the parallel lines. For example, if one alternate interior angle is 75°, the other is also 75°.

• Alternate Exterior Angles

Alternate exterior angles are angles that are located outside the parallel lines. These angles form on the opposite sides of the transversal line. These angles are always equal in measure for a given set of parallel lines. For example, if one alternate exterior angle is 110°, the other is also 110°.

• Consecutive Interior Angles (Co-Interior Angles)

Consecutive interior angles are created on the inside of the two parallel lines and they are on the same side of the transversal line. These are supplementary types of angles, which means that the sum of these angles is always 180°. For example, if one angle is 80°, the other must be 100° to add up to 180°.

4.0Types of Angles in a Clock

We can see many types of angles in a clock based on its amplitude. The analogue clock has three hands to indicate three different time units: hour hand, minute hand, & second hand. A clock has a total of twelve divisions that together form a complete angle of 360°.

• Acute Angles: When the hands are between 0° and 90° (e.g., 10:10).
• Right Angles: When the hands form a 90° angle (e.g., 3:00 or 9:00).
• Obtuse Angles: When the hands form an angle greater than 90° (e.g., 8:20)
• Straight Angles: When the hands form a 180° angle (e.g., 6:00)
• Reflex Angles: When the angle is greater than 180° (e.g., 11:05)

5.0Types of Angles Chart

The types of angles chart provides an easy representation of the angle types and their respective measures. It is a useful tool for students to remember the information, and it comes in handy during revisions before the examination.

6.0Types of Angles Examples

Here are some real-life types of angles examples for a better understanding of the concepts discussed in the guide. 

• Acute Angles: Open scissor.
• Right Angles: The corner of a table.
• Obtuse Angles: The angle in a reclining chair.
• Straight Angles: A completely unfolded laptop.
• Reflex Angles: The angle in a swinging door beyond 180°.
• Complete Angles: The rotation of a bicycle wheel.

7.0Conclusion

Understanding the types of angles in geometry has a multitude of benefits. One can apply this knowledge to academics, engineering, or daily life applications. Now that you have a complete guide on angles and types of angles, you must practice diligently to get perfect at the calculations.