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Angle and its Measurement class 11 th

As you are studying Angles and Measurements class 11 th in this course, here are some highlighted points and terms you need to study.

When you have mastered the concept of points, lines, and planes, you can then think about what happens when two lines or rays meet at a point. This creates an angle between them.

We use angles throughout geometry to analyze shapes like polygons and polyhedrons. We also use angles to describe the behavior of lines, so we should become acquainted with angles, their terms, and how we measure and describe them. In this course, you will better understand angles and measurements. 

Angle measurement Requirements : 

1) Protractor

2) Set-squares

4) Ruler

5) Compass

6) Divider

To Measure angle Protractor is used. For example, circular or semicircular protractors are usually made of transparent plastic, so they can be placed over shapes on a piece of paper and used to measure angles.

When studying angles and Measurements, these are the terms you need to understand:

What is an Angle?

An Angle is a figure which is formed by two rays or lines that shares a common endpoint in Plane Geometry.

An angle is a combination of two rays (half-lines) with a common endpoint. The latter is known as the vertex of the angle and the rays as the sides, sometimes as the legs, and sometimes the arms of the angle.

How many types of Angle are there? Enlist them.

The different types of angles based on their measurements are: 

Acute Angle - a point with is under 90 degrees

Right Angle - a point which is exactly 90 degrees.

Obtuse Angle - a point which is more than 90 degrees and less than 180 degrees.

Straight Angle - A point that is precisely 180 degrees.

The section starts with the rudiments. A point is a turn of a beam from its underlying point to its terminal point.

1) Initial side

2) Terminal side

3) Positive angle

4) Vertex

5) Negative angle

Properties of Angles

Angles are measured in degrees, a measure of circularity or rotation.

One full rotation from the center of a circle is 360°, which would bring you back to your original position. As a result, a half-circle is 180°, and a quarter-circle, or right angle, is 90°.

How do Degrees and Radians differ from each other?

To describe or measure an angle, we usually use 'degrees' as the unit of measurement. You may find that angles are sometimes referred to in radians, however.

The radian is the standard unit of measurement for angles in the Standard International System (SI).

Our previous discussion mentioned that the full rotation of angles through a circular arc is 360°. Therefore, it is also equal to 2π radians, where π (pi) is a special number equaling (approximately) 3.142 (there is more about π on our page on Special Numbers and Concepts).

Radians are represented by 360/2* = 57.3°. Pi is also used to calculate areas and circumferences of circles and to calculate sphere volumes. For more information, review the course and understand it in detail. After completing this course you will be able to solve the maths chapter solution.

Zero angles:

The angle so formed is zero if the ray OA is no longer rotating, that is it is not rotating. The initial arm is then a terminal arm OB.

A rotation angle is formed when the initial ray OA coincides with the terminal ray OB after one complete rotation.

Straight angle: 

A straight angle is formed when, after a rotation, the rays from the initial angle OA and the terminal angle OB face each other in opposite directions.

Right angle: 

The right angle of one-fourth of one rotation angle is also half of a straight angle. Four right angles make up one rotation angle.

Angle in a Quadrant: 

If the terminal ray of a directed angle lies in a particular quadrant in standard position, then the angle is said to belong to that quadrant Angles

A quadrantal angle is a directed angle whose terminal ray lies along the X-axis or the Y-axis of a standard position.

Co-terminal angles: 

In mathematics, co-terminal angles are directed angles of different amounts of rotation with the same initial and terminal ray positions.

Basic Requirement

  • Anyone who wants to learn

  • SSC passed

Skills Covered

  • Degree to radian conversion

  • Length of the arc

  • Area of the sector

Expert Review

Angle and its measurement Lesson from Std Class 11th
It Includes all the Exercise and its solution with proper explanation for the student from Class 11th.

Topics students will learn in this course are as follows -

1. Length of the arc of a circle

2. Area of the sector

3. Radian Measurement

4. Degree Measurement

5. Radian to degree conversion of angle and vice versa.

Get Certified

You will receive an industry-recognized Certification from TeacherDada after completing the course. You can also share your Certificate in the Certifications section of your LinkedIn profile, CVs, resumes, and other documents.

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Course creator

                                 Amit Patil

Amit Patil

B.E Mechanical Engineering from Mumbai University. 6 years of teaching experience for JEE, BITSAT, VITEEE, etc