How To Use A Protractor To Draw Angles

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Using a protractor can be tricky, particularly if yous are using one with ii sets of numbers. If you sympathize the concept of astute and birdbrained angles, nevertheless, learning how to employ a protractor is easy. It is first necessary to sympathise the features on a protractor, so that you lot sympathise how to apply it. Once yous accept this understanding, you can speedily use 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. One vector of your angle should e'er line up with the base line.
- Since a straight line is 180 degrees, the base line marks a 180-caste angle.
two

Locate the origin pigsty. This is a pocket-size hole at the midpoint of the base of operations line. You use this hole to create the vertex of the angle. The vertex is the indicate at which the two vectors see, creating an bending.

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3

Locate the degree measurements. Most protractors take 2 sets of numbers, an outer fix and an inner set. Which set of numbers y'all utilise will depend on whether your angle opens to the right, or opens to the left. The sets of numbers tin can exist ready differently on each protractor, and then y'all need to effigy out for yourself which set of numbers to use. To make up one's mind which set of numbers to use, you lot need to understand right, acute, and obtuse angles.^[ane]

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i
Place a right bending. A right angle has a measurement of ninety degrees.^[2] A xc-degree angle will look similar the corner of a square. The two vectors of the angle are perpendicular, and open exactly halfway towards a straight line (which is 180 degrees).
- When you lot line up the base line of the protractor with i vector of a right angle, the other vector volition line up with the ninety-degree marker of the protractor. This is halfway betwixt either side of the protractor. Both the inner and outer sets of numbers on the protractor will show xc degrees at this point.
2
Identify an acute angle. An astute angle has a measurement of less than 90 degrees.^[iii] This means that the two vectors will be closer together than they are in a xc-caste bending. They will open less than halfway towards a straight line. If the angle you are drawing is less than xc degrees, brand sure y'all use the ready of numbers that gives y'all the smaller angle.
- For example, a 45-caste bending is acute, because 45 is less than 90. If you line upward 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. Y'all volition know which line to look at because you know it is an astute angle, and an acute angle should exist less open than a 90-degree bending.
iii
Place an obtuse bending. An obtuse angle has a measurement of more 90 degrees.^[4] The two vectors of an obtuse angle are farther autonomously than they are in a 90-degree angle. They will open more than than halfway to a straight line. If the bending you are drawing is more than 90 degrees, brand certain y'all use the set of numbers that gives y'all the larger angle.
- For example, a 120-degree angle is birdbrained, because 120 is greater than 90. If you line up the base line of the protractor with one vector of a 120-degree angle, the other vector will line upwardly with the 120-degree mark and the 60-degree marking. If you know you are looking for an birdbrained bending, you know to use the 120-caste mark, considering an birdbrained bending should be more open than a 90-caste angle.
iv
Ignore the orientation of the bending. Whether an angle opens to the left or to the right does not touch on whether it is right, acute, or birdbrained. All that matters is the measurement of the angle in degrees. The fashion the angle opens but changes the gear up of numbers you will expect at on your protractor.
- For example, if a 45-caste angle opens to the right, you lot might have to look at the inner gear up of numbers. But if you were to turn that angle around so that it opens to the left, information technology would still measure 45 degrees, but this time when you lot measure information technology, you lot would take to look at the outer set up of numbers.
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one
Decide the measurement of the angle you are cartoon. Annotation whether the angle is acute or birdbrained.
- For instance, you lot might need to draw a 45 caste angle. Since 45 is less than 90, this is an acute angle. That means yous will use the set of numbers that gives you the smaller angle, since the angle volition open up less than halfway towards a straight line.
two
Draw a straight line. You can do this using a ruler or the straightedge of your protractor. This line will course the beginning vector of your angle.
- The length of the line does not necessarily affair, but the longer it is, the easier it will be to line it up to the base line. The all-time method is to draw a line running the length of the protractor's edge.
3

Align the origin hole at about the midpoint of the line. Brand sure that the base line of the protractor lines up with the line you lot drew.^[5] Draw a midpoint for your reference.
4
Marker the bending measurement. Make this marking along the outside of the protractor by the appropriate degree mark. To make certain you are making the marking at the correct place, ask yourself the following questions:
- Will my angle open up to the right, or to the left?
- Is my angle less (astute) or greater (obtuse) than 90 degrees?
5

Draw the 2d vector of the bending. Use a ruler or straightedge to join the origin signal on the base line to the degree mark.
6

Erase whatsoever unnecessary lines. You volition likely need to erase part of the base line yous drew. Otherwise, you may have two angles drawn, and it may exist unclear to another person which is your intended angle.

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Add together New Question

Question

What are angles opening to the left chosen?

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

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

Utilise the outside, curved border.
Question

What about the angle that we want to make in the circle?

If you're referring to a central angle, describe 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 describe whatsoever key angle upward to 180°, using another bore (or radius) to consummate the angle.
Question

Are 3 sides (sss) congruent or not?

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

How do I draw 180 degrees?

A 180° angle forms a straight line. The vertex of the angle can be considered to be whatsoever bespeak on that line with the rays of the angle extending out in both directions from the vertex.

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