How To Use A Protractor To Draw An Angle

Download Article

Using a protractor can be tricky, especially if you are using 1 with two sets of numbers. If you understand the concept of acute and obtuse angles, however, learning how to utilise a protractor is easy. It is beginning necessary to understand the features on a protractor, so that you understand how to use it. Once you have this understanding, you can quickly apply a protractor to make whatsoever size angle between 0 and 180 degrees.

1
Locate the base line. This horizontal line is at the bottom of the protractor. 1 vector of your angle should always line up with the base line.
- Since a directly line is 180 degrees, the base line marks a 180-degree bending.
2

Locate the origin hole. This is a pocket-size hole at the midpoint of the base line. You apply this pigsty to create the vertex of the bending. The vertex is the signal at which the ii vectors meet, creating an bending.

Advertisement
iii

Locate the caste measurements. Nigh protractors accept two sets of numbers, an outer ready and an inner set up. Which set up of numbers you lot use volition depend on whether your angle opens to the correct, or opens to the left. The sets of numbers can exist set upwards differently on each protractor, so yous demand to figure out for yourself which set up of numbers to use. To determine which ready of numbers to use, you demand to understand right, acute, and obtuse angles.^[1]

Advertisement

one
Place a right bending. A correct angle has a measurement of 90 degrees.^[2] A 90-degree bending will wait like the corner of a foursquare. The ii vectors of the angle are perpendicular, and open exactly halfway towards a direct line (which is 180 degrees).
- When you line up the base line of the protractor with one vector of a right bending, the other vector will line up with the 90-degree mark of the protractor. This is halfway between either side of the protractor. Both the inner and outer sets of numbers on the protractor will show 90 degrees at this betoken.
2
Identify an astute angle. An astute angle has a measurement of less than 90 degrees.^[3] This ways that the 2 vectors will be closer together than they are in a 90-degree angle. They will open less than halfway towards a straight line. If the angle you are drawing is less than 90 degrees, brand sure you utilise the set of numbers that gives you the smaller bending.
- For example, a 45-degree angle is acute, because 45 is less than xc. If yous line up the base line of the protractor with one vector of a 45-degree angle, the other vector will line up with the 45-degree mark and the 135-degree mark of the protractor. You lot will know which line to look at because you know it is an acute bending, and an acute angle should be less open than a 90-degree angle.
3
Place an obtuse angle. An obtuse angle has a measurement of more than than 90 degrees.^[4] The two vectors of an obtuse bending are farther apart than they are in a 90-degree bending. They volition open more than than halfway to a directly line. If the angle you are cartoon is more than 90 degrees, brand sure you use the set of numbers that gives you the larger bending.
- For instance, a 120-caste angle is obtuse, considering 120 is greater than 90. If y'all line up the base of operations line of the protractor with 1 vector of a 120-degree angle, the other vector will line up with the 120-degree mark and the 60-degree mark. If you know you are looking for an obtuse angle, y'all know to utilise the 120-caste marker, considering an birdbrained bending should be more than open than a 90-degree bending.
4
Ignore the orientation of the angle. Whether an angle opens to the left or to the right does not touch whether information technology is right, acute, or obtuse. All that matters is the measurement of the angle in degrees. The way the angle opens but changes the set of numbers you lot will look at on your protractor.
- For instance, if a 45-degree angle opens to the correct, you might have to look at the inner set of numbers. Simply if yous were to turn that angle effectually then that it opens to the left, it would withal measure 45 degrees, but this fourth dimension when y'all mensurate information technology, you would have to await at the outer gear up of numbers.
Ad

1
Decide the measurement of the angle you are drawing. Note whether the angle is acute or obtuse.
- For example, yous might need to depict a 45 degree angle. Since 45 is less than 90, this is an acute angle. That ways you will use the set of numbers that gives you lot the smaller angle, since the angle will open less than halfway towards a straight line.
2
Depict a straight line. You can do this using a ruler or the straightedge of your protractor. This line will form the first vector of your angle.
- The length of the line does not necessarily matter, but the longer information technology is, the easier it will be to line it upwardly to the base line. The best method is to draw a line running the length of the protractor's edge.
iii

Align the origin hole at about the midpoint of the line. Make sure that the base line of the protractor lines up with the line you drew.^[5] Draw a midpoint for your reference.
iv
Marking the bending measurement. Make this mark along the exterior of the protractor by the appropriate degree mark. To make sure you are making the marking at the correct identify, ask yourself the following questions:
- Will my angle open to the right, or to the left?
- Is my angle less (acute) or greater (obtuse) than 90 degrees?
five

Depict the 2nd vector of the angle. Utilise a ruler or straightedge to join the origin indicate on the base of operations line to the caste mark.
half-dozen

Erase whatever unnecessary lines. You volition probable need to erase office of the base line yous drew. Otherwise, you lot may have ii angles drawn, and it may exist unclear to another person which is your intended angle.

Advertising

Add New Question

Question

What are angles opening to the left called?

The type of angle is not determined by which manner information technology opens. An angle is either acute, correct, or birdbrained, no thing which way it opens. All that matters is the size of the angle. For instance, you can draw a 45 degree angle opening to the left, or opening to the right. Either fashion, it is an acute angle.
Question

How do I employ a protractor that doesn't have a hole?

Use the outside, curved edge.
Question

What about the bending that nosotros want to brand in the circle?

If yous're referring to a fundamental angle, draw a diameter. Line up the bottom of the protractor with the diameter so that the midpoint of the protractor aligns with the center of the circle. Use the protractor to draw any central angle up to 180°, using some other diameter (or radius) to complete the angle.
Question

Are 3 sides (sss) congruent or not?

Yes, if each side of a triangle is congruent with (the same length as) a side of another triangle, the ii triangles are congruent.
Question

How do I draw 180 degrees?

A 180° angle forms a directly line. The vertex of the angle tin exist considered to exist any point on that line with the rays of the bending extending out in both directions from the vertex.

Inquire a Question

200 characters left

Include your email address to get a message when this question is answered.

Submit

An acute angle is an angle from 0 to 89 degrees, which is less than a correct angle.
A right angle is an angle that is exactly 90 degrees.
An obtuse bending is an angle greater than a right angle, but less than a straight angle. It can be anything ranging from 91 degrees to 179 degrees.
A direct angle measures to 180 degrees.