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.
It is a circular protractor which is marked in degrees from 0° to 360° 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. 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. 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°. 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. 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. We will learn how to construction of an angle using a protractor. Let us draw an angle whose measure is 60°. Use a ruler to draw YZ. Now, place the protractor over YZ such that the baseline of the protractor coincides with YZ and midpoint of the baseline coincides with point In worksheet on angles you will solve 10 different types of questions on angles. Classify the following angles into acute, obtuse, right and reflex angle: (i) 35° (ii) 185° (iii) 90° Types of angles are discussed here in this lesson. Angles are classified on the basis of their measures. Acute Angle: An angle whose measure is less than 90° is called an acute angle. Right Angle: An angle whose measure is 90° is called right angle. Angle is discussed here in details. In our daily life we come across different objects having two arms hinged at a point. For example, hands of a clock, two arms of a divider, and two sharp edges of a scissors are all hinged at a point and thus are inclined to each other. ● Angle. Interior and Exterior of an Angle. Measuring an Angle by a Protractor. Construction of Angles by using Compass. Geometry Practice Test on angles. 5th Grade Geometry Page Didn't find what you were looking for? Or want to know more information
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It is a semicircular protractor which is marked in degrees from 0° to 180° from left as shown in adjoining figure.
Thus we find ∠ AOB = 60°.
2. Use your protractor to draw 90°.
Thus we find ∠ AOB = 90°.
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