How to Use a Protractor to Draw a Circle

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A protractor is a handy tool used to mensurate and describe angles. Generally, semi-circular in shape, protractors are too bachelor in full-circle, 360-degree versions. If i await at the object has you completely dislocated, never fear; learning to use the tool is uncomplicated. By agreement how the parts of a protractor are used together and following a few easy steps, y'all volition exist an angle expert in no time.

1. 1

   Approximate the measure of your angle. Angles can be classified in three ways: acute, obtuse, and right. Acute angles are narrow (less than 90 degrees), obtuse angles are wide (greater than 90 degrees), and right angles are exactly 90 degrees (ii lines perpendicular to each other).^[1] You lot tin can easily place by eye, the category of angle you are trying to measure. Doing this step first helps you identify which calibration to use on the protractor.

   • At a glance, nosotros tin tell this angle is acute considering it is less than 90 degrees.

2. 

   ii

   Place the origin over the center point, or vertex, of the angle you lot desire to mensurate. ^[2] The small hole in the middle of the base of the protractor is the origin. Marshal the vertex of the angle with the center of the cross in the origin.

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3. 3

   Rotate the protractor to align 1 leg of the angle with the baseline. Maintain the vertex of the bending in the origin and gently rotate the protractor and then that one of the legs of the angle falls on the baseline of the protractor.^[3]

   • The baseline is parallel to the border, simply is not the apartment edge of the protractor. It is aligned with the center of the origin and the line projects to the start of the scale on either side.

4. 

   4

   Follow the opposite leg of the angle upwardly to the measurements on the protractor'due south arc. If the line does not pass through the protractor's arc, extend the angle's line until information technology does. Alternatively, you lot tin can align the edge of a piece of paper with the angle's leg to pass beyond the border of the protractor, continuing the line of the angle. The number the line passes through is the angle's measurement in degrees.

   • In the to a higher place case, the angle measure is 30 degrees. Nosotros know to use the smaller scale because we determined that our angle was less than ninety degrees in the start step. If the bending was birdbrained, we would utilize the calibration that indicated an bending larger than 90 degrees.
   • Initially, the measurement calibration may seem confusing. Most protractors have two opposing ruler grids, one on the inner side of the arc and one on the outer. This makes the tool handy for measuring angles originating from either direction.

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1. 

   1

   Draw a straight line. The line is your reference line and the showtime leg of your angle. It will be used to determine the position at which y'all draw the 2d leg of the angle. Information technology'due south mostly easiest to describe the direct line in a horizontal position on the paper.

   • You lot tin use the flat edge of your protractor to describe this line.
   • The length of the line doesn't affair.

2. 

   ii

   Place the origin of the protractor at ane end of the line. This point volition exist your angle'due south vertex. Mark the newspaper where the vertex is placed.^[4]

   • You don't take to place the betoken at the border of the line. It can be placed anywhere on the line, but is easier only to apply the end of the line.

3. 

   three

   Find the degree of the bending y'all wish to draw on the protractor's appropriate scale. Align your reference line with the protractor's baseline and mark the paper at the degree of measurement. If you are drawing an acute angle (less than 90 degrees), use the calibration with the smaller numbers. For obtuse angles (greater than 90 degrees), utilize the scale with larger numbers.

   • Retrieve, the baseline is parallel to the border, only is not the flat edge of the protractor. It is aligned with the heart of the origin and the line projects to the start of the scale on either side.
   • In the to a higher place example, the angle is twoscore degrees.

4. 

   iv

   Draw the second leg to complete the angle. Using a ruler, the flat edge of your protractor or another straight edge, connect the vertex with the marked caste, drawing the second leg. This second leg completes your angle. To verify you lot've drawn the angle accurately, use the protractor to measure out information technology.

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Add New Question

• Question

  When practise I use the outer scale of the protractor?

  

  The inner calibration is for angles that open to the correct and the outer scale of the protractor is used to measure out angles that open to the left .

• Question

  How tin I tell whether I need to use a larger or smaller protractor?

  

  The angle on a protractor will always be the same.You lot may find information technology easier to have a pocket-size protractor when only drawing a pocket-size line from the angle you lot are measuring.

• Question

  Why does the protractor have readings on both sides?

  

  So y'all can read angles form different directions. Information technology's kind of similar opposite/mirror images.

• Question

  How do I find if the bending is negative or positive?

  

  All angles -- as typically expressed in the context of geometry -- are positive. Any bending y'all measure with a protractor may be thought of every bit positive.

• Question

  Why is it important to use a protractor?

  

  If you desire to precisely find the degrees in an angle, the protractor is probably the best tool.

• Question

  Is an obtuse or acute bending better?

  

  There's no better angle, they are only measurements.

• Question

  Does it affair what company the protractor is made by?

  

  No need to worry what company the protract is made by. They all give you accurate measurements of angles, regardless of the company.

• Question

  Should I start measuring from the left or from the right?

  

  Y'all can measure from either finish.

• Question

  Is a right bending 90 degrees?

  

  Yeah. A correct angle is 1 that measures 90 degrees. That is common noesis for any student of math to memorize.

• Question

  How do I determine which scale to utilise when I use a protractor to describe or measure an bending?

  

  The scales are identical. One increases from the left side; the other increases from the right side.

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Things You lot'll Demand

• pencil/pen
• paper
• protractor
• ruler (optional)

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Article Summary Ten

You can use a protractor to measure and describe angles. To measure angles with a protractor, first place the centre bespeak along the lesser edge of the protractor over the vertex of the angle you're measuring. Line up the lesser edge of the protractor with one leg of the angle. Follow the other leg of the bending up to the protractor's arc to see what number it intersects with and find the degree of the bending. If the angle is facing to the right, use the bottom row of numbers on the protractor. If the angle is facing left, apply the top row of numbers. To draw an angle with a protractor, first identify the center betoken along the bottom edge of the protractor where you want the vertex of the angle to be. Draw a pocket-size dot in the hole on the protractor to marker the vertex. Then, line the bottom edge of the protractor up with the vertex and draw a straight line forth it. Now, find the hash marker on the protractor that corresponds with the angle you lot desire to draw, and draw a modest dot exterior of it. Rotate the protractor and line the lesser edge up between the vertex and the small dot. Finally, use the lesser border of the protractor every bit a straight border to draw a line between the ii points. Proceed reading the article if you want to acquire how to draw angles with your protractor!

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