Subscribe to our YouTube channel for the latest videos, updates, and tips.


Measuring an Angle by a Protractor

In measuring an angle by a protractor, first we need to know what a protractor is.


Protractor:

We measure the size of an angle by using protractor. The protractor is in the shape of a semicircle. The semicircle is divided into 180 equal parts which show angle measurements from 0° to 180°.

The protractor has two sets of measurements. The marking on the inner circle is 0° to 180° in the opposite direction to the markings on the outer circle.

It is an instrument for measuring or constructing an angle of a given measure. It is a circular or semicircular piece of metal or plastic.

Measuring an Angle by a Protractor



It is a circular protractor which is marked in degrees from 0° to 360° from left as shown in adjoining figure.



Measuring an Angle by a Protractor



It is a semicircular protractor which is marked in degrees from 0° to 180° from left as shown in adjoining figure.

To measure an angle ABC, we place the mid point of the protractor on the vertex O of the angle. The base OA arm falls along with the base line of the protractor as shown in the figure below.

Measuring Angles

The angle is measures on the protractor counting from 0 up to the point where the arm OB lies. In the above figure ∠AOB = 60°. 

The angle which is formed outside is known as the exterior angle. 

Interior and Exterior Angles

In the above figure ∠2 is the exterior angle and ∠1 is known as interior angle.


For Example:

1. Use your protractor to draw 60°.

Use your protractor to draw 60°

The centre O of the piece is also the midpoint of its base line. In order to measure ∠AOB, place the protractor in such a way that its centre is exactly on the vertex O of the angle, the base line lies along the arm OA. We need to read the mark through which the arm OB passes, starting from O on the side A, as we observe in the above figure.

Thus we find ∠ AOB = 60°.



2. Use your protractor to draw 90°.

Use your protractor to draw 90°

The centre O of the piece is also the midpoint of its base line. In order to measure ∠AOB, place the protractor in such a way that its centre is exactly on the vertex O of the angle, the base line lies along the arm OA. We need to read the mark through which the arm OB passes, starting from O on the side A, as we observe in the above figure.

Thus we find ∠ AOB = 90°.



● Angle.

Interior and Exterior of an Angle.

Measuring an Angle by a Protractor.

Types of Angles.

Pairs of Angles.

Bisecting an angle.

Construction of Angles by using Compass.

Worksheet on Angles.

Geometry Practice Test on angles.

 






5th Grade Geometry Page 

5th Grade Math Problems 

From Measuring an Angle by a Protractor to HOME PAGE




Didn't find what you were looking for? Or want to know more information about Math Only Math. Use this Google Search to find what you need.



New! Comments

Have your say about what you just read! Leave me a comment in the box below. Ask a Question or Answer a Question.




Share this page: What’s this?

Recent Articles

  1. Worksheet on Average | Word Problem on Average | Questions on Average

    May 19, 25 02:53 PM

    Worksheet on Average
    In worksheet on average we will solve different types of questions on the concept of average, calculating the average of the given quantities and application of average in different problems.

    Read More

  2. 8 Times Table | Multiplication Table of 8 | Read Eight Times Table

    May 18, 25 04:33 PM

    Printable eight times table
    In 8 times table we will memorize the multiplication table. Printable multiplication table is also available for the homeschoolers. 8 × 0 = 0 8 × 1 = 8 8 × 2 = 16 8 × 3 = 24 8 × 4 = 32 8 × 5 = 40

    Read More

  3. How to Find the Average in Math? | What Does Average Mean? |Definition

    May 17, 25 04:04 PM

    Average 2
    Average means a number which is between the largest and the smallest number. Average can be calculated only for similar quantities and not for dissimilar quantities.

    Read More

  4. Problems Based on Average | Word Problems |Calculating Arithmetic Mean

    May 17, 25 03:47 PM

    Here we will learn to solve the three important types of word problems based on average. The questions are mainly based on average or mean, weighted average and average speed.

    Read More

  5. Rounding Decimals | How to Round a Decimal? | Rounding off Decimal

    May 16, 25 11:13 AM

    Round off to Nearest One
    Rounding decimals are frequently used in our daily life mainly for calculating the cost of the items. In mathematics rounding off decimal is a technique used to estimate or to find the approximate

    Read More