Want to Master Angles? These Are The 5 Basic Rules of Angles You Must Know

Are you prepared for your Math exam by knowing your angle facts? Having a solid grasp of rules of angles are critical to perform well on your Math tests. Ensure you understand these guidelines before the big day because this guide contains all the essential information.

What is an Angle?

In mathematics, an angle is a geometric figure that represents the amount of rotation between two lines or rays. An angle is formed by two rays that share a common endpoint, called the vertex of the angle, and the two rays are called the arms of the angle.

Angles are typically measured in degrees or radians. A full rotation, or one complete circle, is 360 degrees or 2π radians. An angle less than 90 degrees is called an acute angle, an angle equal to 90 degrees is called a right angle, an angle greater than 90 degrees but less than 180 degrees is called an obtuse angle, and an angle equal to 180 degrees is called a straight angle.

Angles can also be classified as complementary, supplementary, or congruent based on their measure. Two angles are complementary if their sum equals 90 degrees, two angles are supplementary if their sum equals 180 degrees, and congruent angles have the same measure.

In geometry, angles play a crucial role in studying triangles, polygons, circles, and other shapes. They are used to define and describe the relationships between lines and shapes and determine geometric figures’ size and orientation.

There are Various Angles:

  • Acute angles are those that are smaller than 90 degrees.
  • The right angles are precisely 90 degrees.
  • Obtuse angles are more than 90 degrees but less than 180 degrees.
  • Angles with a precise 180-degree measurement are known as straight angles.

Angle Facts for Exams

  • A right angle (90°) is the angle created by two parallel lines.
  • Two parallel lines intersect at an angle.
  • The angle of inclination is the angle formed by a line and a plane.
  • The angle formed by two lines meeting at a point is known as the edge angle.
  • The angle of intersection is the angle created by two intersecting curves.
  • The angle of incidence is the angle formed by a line and a surface.
  • The angle of incidence is the angle formed by two surfaces.
  • The angle of incidence is the angle formed by an edge and a surface.
  • The angle of obliquity is the angle formed by two lines that are not parallel.

How Do You Define & Measure an Angle?

A measure of turning is an angle. Angles can be measured in radians or degrees (°). (rad).

A protractor is required to measure an angle. Measure the angle in degrees or radians by positioning the protractor such that the desired angle is in the centre. A straight angle is one with a measure of 180°.

Describe a Right Angle.

A 90° or 1.57 radian angle is a right angle, and stands for right angles. Obtuse angles are those that are greater than 90°, whereas acute angles are those that are less than 90°.

What is a Reflex Angle?

An angle that is more than 180° but less than 360° is referred to as a reflex angle. The reflexive aspect of this type of angle—the way it circles back on itself—gives rise to its name. In geometry, reflex angles are frequently employed to determine an object’s size and shape. Although it’s doubtful that you’ll ever need to draw a reflex angle in reality, they do exist in nature. For instance, a rainbow typically has an angle between 310° and 360°.

What is The Angle Sum of a Triangle?

Any triangle’s angle sum is always 180 degrees, and this is because a triangle’s three angles always sum to 180°.

Angle Exam Practice Questions

Angles are a fundamental concept in geometry and a crucial topic in mathematics, especially trigonometry, and geometry. By practising angle questions, you can improve your understanding of the properties and relationships of angles, which will help you solve more complex problems. Here are a few reasons why practising angle questions is essential:

  1. Reinforcement of concepts: Practising angle questions regularly helps you reinforce your understanding of the concepts and relationships between angles. This can lead to better retention of the material and a deeper understanding of how to apply these concepts in real-world scenarios.
  2. Identifying patterns: When you practise angle questions, you may notice patterns in the problems asked. This can help you identify the questions you may encounter on an exam and how to approach them.
  3. Improving problem-solving skills: Solving angle questions requires mathematical knowledge and problem-solving skills. By practising these questions, you can improve your ability to identify the critical elements of a problem, think logically, and find a solution.
  4. Building confidence: Practising angle questions can help you build confidence in your ability to solve problems involving angles. This can be especially helpful when taking an exam, where confidence can significantly affect your performance.

It’s crucial to practise angle questions as you study for your maths examinations so that you are familiar with the format and can respond t

o them with assurance on test day. Otherwise, signing up with PFTuition Math will be a good alternative as our experienced teachers provide necessary and suitable practices for our students to help them master each topic like angles.

Tips for Revision

When reviewing angle facts for your maths exams, there are a few essential points to remember.

Make sure you first comprehend the many angles and how to measure them. To correctly respond to queries about angles, you’ll need to be able to do this.

Second, commit to memory the essential angle facts; a few important ones will frequently recur in exam questions.

Practise as much as you can, too! Numerous excellent online tools, including SchoolOnline, and maths textbooks, are available to practise your angle revision.

What are The Five Basic Angle Rules?

1. The sum of the angles in a quadrilateral is 360 degrees.

2. The sum of the angles in a triangle is 180 degrees.

3. Opposite Angles Are Equal

4. The sum of the angles on a straight line is 180 degrees.

5. Exterior angle of a triangle is equal to the sum of the opposite interior angles

What are The Angles Commonly Needed for Exams?

1. Zero Angle (0°)

2. Acute Angle (0° to 89°)

3. Right Angle (90°)

4. Obtuse Angle (91° – 179°)

5. Straight Angle (180°)

6. Reflex Angle (181° – 329°)

7. Complete Angle (360°)

Why are Angles Necessary?

When studying polygons, triangles, and quadrilaterals, angles are crucial.

Can There Be a Negative Angle?

Negative angles are measured in a clockwise manner.


To succeed in your exams, you must master angles. Ensure you measure angles correctly and commit the essential angle data to memory. However if you do find yourself struggling with angles or other maths topics, PFTuition Math would always be ready to lend a helping hand. Do sign up with us now! 

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