#Geometry protractor how to

There are other protractors that are circular in shape which can measure complete 360-degree angles. The common protractor which is used in geometry is in the shape of a semicircle with markings of angles from 0° to 180° on it. Step 5: Mark a point C at 50° and join O to C.Step 4: Since the angle is to be formed on the right-hand side of the protractor, we will use the inner readings and look for 50°.Step 3: Align the baseline of the protractor with the line OB.Step 2: Mark the point O and place the center of the protractor at O.The following steps can be used to draw angles using a protractor.

#Geometry protractor how to

How to Use a Protractor to Draw Angles?Ī protractor can be used to measure and draw angles. A common protractor is in the shape of a semicircle that has an inner and an outer scale with markings from 0° to 180° on it. To reduce errors, align the baseline and vertex properly.įAQs on Protractor What is a Protractor in Geometry?Ī protractor is a simple measuring instrument that is used to measure or draw angles in degrees.If the angle to be measured is on the left-hand side from the center of the protractor, we use the outer readings of the protractor and if the angle to be measured is on the right-hand side of the center, we use the inner readings.

The angle protractor tool and 360° protractor give more precise measurements.

We can also use a 360° protractor to draw a reflex angle.

It is commonly used in the field of architecture, mechanical drawings, and meteorology. Therefore, ∠CAB = 40°.Ī 360° protractor is circular in shape and has readings up to 360° in the clockwise direction.

Step 5: Now using a scale, join A and C.

Step 4: In the inner readings, look for 40º and mark it as point C.

Step 3: Since the angle is drawn on the right-hand side of the vertex we will see the inner readings.

Step 2: Align the baseline of the protractor on AB such that the center of the protractor is placed on point A.

Let us see how to draw an angle of 40º using a protractor. In order to draw angles using a protractor, we use the following steps. This can be verified by the values, that is, 150º + 30º = 180º. It should be noted that ∠AOC + ∠BOC form a straight line and hence add up to 180.

Step 2: Check the reading where the ray OC is formed.

Since we need to measure ∠AOC, which is formed on the left-hand side of the center, we will use the outer readings which go clockwise.

Step 1: Place the baseline of the protractor on line AO such that the centre of the protractor is placed on vertex O.

Now, let us find the measure of ∠AOC using the following steps.

Step 3: Now, identify the reading on the protractor where ray C is extending.

Step 2: Since the angle is formed on the right-hand side of the center, we will use the inner readings which go anti-clockwise.

Step 1: In order to measure the angle ∠BOC, align the baseline of the protractor with the line AB such that the center circle of the protractor is at the vertex O.

In this case, ∠BOC = 120°.įor measuring angles with a protractor, let us use the following steps and relate to the figure given below.

Step 4: If the angle to be measured is formed on the right-hand side from the center of the protractor, we need to use the inner readings of the protractor.

If the angle to be measured is formed on the left-hand side from the center of the protractor, we need to use the outer reading of the protractor.

Step 3: Decide which readings are to be followed.

Step 2: Place the baseline of the protractor on the ray which is the base of the angle.

Step 1: We first need to pIace the center (hole) of the protractor on the vertex O.

Observe the following figure to know how to read a protractor and relate to the steps given below. Each inner reading and outer reading supplements each other, i.e., they add up to 180°.

How to Read a Protractor?Ī protractor can be read using its inner readings or its outer readings depending on the angle that is formed. It has two readings - the outer reading and the inner reading that help to measure a given angle. A protractor is an instrument which is very easy to use.