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. ● 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°.
5th Grade Math Problems
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