The animated diagram above shows how to use a protractor to measure angles. Acute angle. Use on interactive whiteboards, angles can be automatically shown or measured with a protractor. It’s the adorable angle. Determine what type of angle you're measuring. Read the degrees on the bottom line of the protractor where the other side (PQ) crosses. Subtracting the degrees of the acute angle from 180 will give you the degrees of your obtuse angle. You can use the angles to draw a specific type of triangle using a ruler and a protractor. In some diagrams, you may see more than one angle. To determine the number of degrees in an acute angle, connect the 2 rays to form a triangle. How to measure an angle with a protractor: Place the midpoint of the protractor on the VERTEX of the angle. Then, line up one line with the protractor’s baseline, which is the solid line on the bottom with a “0” at either end. Use the arc that allows you to measure an angle in the direction you prefer: clockwise or counter/anticlockwise. To measure any angle,We use protector.It is also called a ‘D’How to use a protractor?So, ∠ABC = 40°How to use a protractor?So, ∠ABC = 40°Measure these angles with a protractorSo, ∠1 = 80°So, ∠2 = 120°So, ∠3 = 90°So, ∠4 = 180° Drag the protractor and rotate it using arrow keys. If one line is more horizontal, it will typically be the easiest one to line up along the baseline. This type of protractor is also called “navigation triangle” or a “nautical protractor” and it’s used for plotting and performing chart work. Bevel the Edge (1 of 2) We'll want the edge of our protractor to be thin while keeping the rest of the … The other side of the angle (PQ) crosses at 60° on the bottom row of the protractor.  X Research source The vertical line creates a right triangle. For a description of the protractor see The Protractor For a demonstration of using the protractor to draw an angle see Drawing Angles with a Protractor The one you read depends on where you place the protractor. To find the area of a triangle, you need to know the length of one side — the base (b for short) — and the height (h). Find the indicated measure on the inner scale of the protractor and sketch the other arm of the angle. Last Updated: June 20, 2019 After this lesson, students will be able to: 1. With a protractor measure an angle of 20 degrees using your meter stick identically to the laboratory set up previously described. Learn more... A protractor is a handy tool that allows you to precisely measure the number of degrees in any angle. Line up one side of the angle with the zero line of the protractor (where you see the number 0). Use the protractor to measure the third angle of the triangle you drew. This smaller acute angle is formed by the straight line you drew and the diagonal line of the original reflex angle. wikiHow is where trusted research and expert knowledge come together. If you look below the straight line, you'll see another angle. Line up one side of the angle with the zero line of the protractor (where you see the number 0). A protractor has two sets of numbers. You can use the protractor to figure out the measure of an angle and draw in the rest of the triangle with the ruler. One set goes from 0 to 180 (on the outer rim) and the other set from 180 to 0 (on the inner rim). Thanks to all authors for creating a page that has been read 15,918 times. For instance if you put it over a paper image of a triangle to measure an interior angle you can line up the tip of the protractor (small detent) but not the swivel point. Be careful which angle you read from By using our site, you agree to our. For more help, including how to calculate reflex angles with a protractor, read on! Otherwise, if your angle opens to the right, use the number in the inner arc. 2. This printable protractor PDF is the actual size and it can be used to make fairly accurate measurements in order to get the right angles when solving geometry problems. Read the degrees where the other side crosses the number scale. Further complementary, supplementary and angles at a point. The arcs are identical in terms of angular measurement. the protractor. For example, if you know you have an obtuse angle, then you know it is going to be more than 90 degrees. If your angle opens to the left, you should note the number on the outer arc of the protractor. The protractor is easier to use if you always line up one of the lines of the angle along the baseline of the protractor. Offered here is one of the arms of an angle tracing the left or right zero of the protractor already in place. The other arc begins with 0° on the left side. This is a protractor, it helps you measure angles (in degrees): Have a look at this animation (press the play button) to see how to make a neat angle using a protractor and ruler: Protractors usually have two sets of numbers going in opposite directions. If you get a smaller number from your protractor, you're likely looking at the wrong scale. What are the lengths of the horizontal leg and vertical leg of the right triangle formed? T-Bevel. CCSS 4.MD.C.6 Measure angles in whole-number degrees using a protractor. A right angle is exactly 90 degrees. Place the midpoint of the protractor on the vertex of the angle. Drag the protractor and rotate it using arrow keys. It’s any angle that … Read the degrees where the other side crosses the number scale. So the top half of the triangle shown above is a right triangle with hypotenuse d and leg e/2. No matter how wide, the direction the alligator is pointing when its "jaws" are closed is the direction the angle opens. Line up one side of the angle with the zero line of the protractor (where you see the number 0). The arc around the vertex shows you which angle you're supposed to find the value of. If an angle is less than 90 degrees, it's an acute angle. You may find it easier to measure if you turn your paper so that the acute angle is facing straight up. Try to measure the angles A, B and C inside the triangle. wikiHow's. When we construct, or draw, geometric figures, we often need to bisect lines or angles.Bisectmeans to cut something into two equal parts. Read the degrees where the other side crosses the number scale. To make sure you're right on the vertex, it can help to make a little dot inside the center of your protractor. Explore how to use a protractor and identify acute, obtuse, straight and reflex angles. The typical protractor is made of clear plastic and has two sets of numbers around the edge. 6 Measure the direction of RV with a protractor and add this value along with. 6 measure the direction of rv with a protractor and. The numbers you use depend on whether the angle you're measuring is acute (less than 90 degrees) or obtuse (more than 90 degrees but less than 180). Demonstrate that the measures of the internal angles of a triangle add up to 180 degrees 3. How to Measure an Angle Using a Protractor, https://www.dummies.com/education/math/geometry/measuring-and-making-angles/, https://www.bbc.com/bitesize/articles/zpjh97h, https://www.bbc.com/bitesize/guides/zrck7ty/revision/4, https://www.onlinemathlearning.com/measuring-angles.html, https://www.edplace.com/blog/what-are-reflex-angles, consider supporting our work with a contribution to wikiHow. The sine of angle A, is sin(A) = .5e/d. The arc around the vertex shows you which angle you're supposed to find the value of. A straight angle. triangle shown above is a right triangle with hypotenuse d and leg e/2. % of people told us that this article helped them. Measuring angles accurately In this video you will learn how to use a protractor to measure angles accurately. Drag the protractor and rotate it using arrow keys. 3 Ways to Measure an Angle Without a Protractor - wikiHow Best www.wikihow.com. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. If you're dealing with a reflex angle (more than 180 degrees but less than 360), you'll have to do an additional calculation. X Use your protractor to measure an angle that is greater than 90 degrees. To draw an obtuse triangle, begin by drawing the obtuse angle. Protractors usually provide numbers in 10s. Easy measure angles, using interactive whiteboard angle simulator. Otherwise, you'll have to do more calculations to determine the degrees in the angle. Actually, it’s just a pinch. Labeling an angle acute or obtuse helps you reading the protractor.  X Research source In some diagrams, you may see more than one angle. Research source. One arc begins with 0° on the right side. This article was co-authored by our trained team of editors and researchers who validated it for accuracy and comprehensiveness. When in doubt think "should this angle be bigger or smaller than 90° ?". Focus on constructing triangles from three measures of angles or sides, noticing when the conditions determine a unique triangle, more than one triangle, or no triangle. But A is one half of the angle we have to measure, and therefore, the angle = … Once your protractor is positioned correctly, see what number the other line of the angle crosses. References. Always place the protractor so that one side of the angle lines up with one of the zeros. Take care to … We know ads can be annoying, but they’re what allow us to make all of wikiHow available for free. wikiHow's Content Management Team carefully monitors the work from our editorial staff to ensure that each article is backed by trusted research and meets our high quality standards. Line up the short end of your ruler with the bottom ray, then draw a vertical line intersecting the other ray using the long side of your ruler. Include your email address to get a message when this question is answered.  Measure these values with another meter stick. Obtuse angles, on the other hand, are more than 90 degrees but fewer than 180. For more help, including how to calculate reflex angles with a protractor, read on! Sometimes the line of the angle may not line up perfectly with a number, and if that’s the case, just count the hash marks on the outside edge to figure out the degrees. We use cookies to make wikiHow great. Place the center of your protractor on the vertex of the angle. Try to measure the angles A, B and C inside the triangle. At the bottom of your protractor, you'll see a little hole in the center. Typically this hole has vertical and horizontal lines crossing it, so you can line up the protractor exactly. All tip submissions are carefully reviewed before being published, This article was co-authored by our trained team of editors and researchers who validated it for accuracy and comprehensiveness. {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/8\/83\/Measure-an-Angle-Using-a-Protractor-Step-1-Version-2.jpg\/v4-460px-Measure-an-Angle-Using-a-Protractor-Step-1-Version-2.jpg","bigUrl":"\/images\/thumb\/8\/83\/Measure-an-Angle-Using-a-Protractor-Step-1-Version-2.jpg\/aid6897726-v4-728px-Measure-an-Angle-Using-a-Protractor-Step-1-Version-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"