Specific instruments are used in geometry, engineering, and mechanics to create wonderful and accurate figures. Therefore, in this case, two valuable tools have usually used a compass and a protractor, which is today’s article topic.
These tools are used by math students in class and drafting experts in the workplace. On maps, both instruments estimate, illustrate, and record ranges. But they differ in terms of their history, workings, and applications.
The basic difference between a compass and a protractor is that a compass is a magnetic tool that is used to confine the primary directions whereas a protractor is a device that protracts or draws out things.
This article summarizes the difference between these two tools and the correct guidelines for utilizing them in your work. After mastering the fundamental skills, you can use them for various purposes like bisecting the lines, drawing and dividing the circles, and many other things.
Their prices depend on your work, as various compasses and protractors serve specific applications.
Before moving on to their disparities, I have gathered some information about their functions, so let’s discuss them first.
A Protractor: D-shaped Tool
It is a measuring instrument mainly used in the geometrical part of mathematics.
Some people refer to the letter “D” as a protractor since it represents one. It is made of glass or plastic, and in addition to being used to measure and draw angles, engineers also use it to create engineering drawings.
Protractors can be straightforward half-discs or complete circles. Those with more advanced and sophisticated technologies that involve a single or perhaps more swinging arms.
Many protractors express angles in degrees, while a radian protractor calculates angles in radians. The majority of them have 180° equal segments. Degrees are further subdivided into arcminutes by some precision protractors.
You can download a protractor on your phone to take measurements of the angles throughout the entire length of your phone. You can achieve this by using a clinometer.
A target angle can be chosen. An elevated scale will be shown as you get closer to the goal angle or make significant 45° steps.
Types of Protractor
There are various types of protractors commonly used each having its distinctive design and function. Some of the types are given in the table below.
| Types of Protractors | Details | Applications |
| Bevel Protractor | A graduated scale that is circular in shape having a pigmented arm utilized to estimate or construct angles; The angle calculated by using the bevel protractor is recorded in minutes and degrees | Used to analyze the block V; Used to investigate the bevel-type face; Used to estimate the sharp angles |
| Medical Protractor | Specially created for the medical sector for mechanical diversion and deformities in the bones; It has a circular body with two arms: a fixed arm and a rotating arm | Used to observe patients; Used to measure Joints deformities; Easy to use and light in weight |
| Miter Protractor | It is ideal for the use of architects, plumbers, and carpenters who utilize it for the measurement of angles; They conclude perfect estimations out of the miter edges | Used by professionals for calculating miter cuts; It can estimate different edge angles |
| Semi-circle Protractor | A protractor which is half a foot in diameter is used to calculate angles to ½ degrees; It constitutes of brass or silver and aids in mapping and geological work | Used in the education department to understand geometry; Used mostly in drawings |
| Quarter-circle Protractor | It has ¼ of a circular body having both of its sides cuts presenting a 90° edge; An uncommon tool used by professionals only | Used in architectural engineering; Employed in meteorological studies |
| Square Protractor | It is square in shape having two scales: inner ranges from 0° to 360° and outer indicated in mm; The inner scale must always be located toward the north | Used by military personnel for locating enemies on maps |
| Digital Protractor | It is an electronic device that gives the result on the screen; It may have two types: single-arm and double-arm digital protractor | Used in laboratories where accurate results are required; It can also be used in various industries |
Compass: A V-shaped Tool
A compass is another effective measuring instrument for making arcs and circular shapes in geometry.
It is a “V-shaped” tool made of metal or plastic. The accessories of a compass feature a clamp for firmly holding a pencil. The other side has a pointy end for gripping the paper while the pencil glides across it.
The primary uses of a compass include:
- Sketching
- Drawing arcs
- Drawing circles
- Drawing figures
- Bisecting lines
- Determining midpoints
Working
You must adequately place both compass’s ends onto the paper so that they stick without creating hindrance to exact drawings.
When both pencil and compass hit together, the compass stands perpendicular to the surface of the page. For creating a circle of various radii, adjust the compass by varying the distance between its arms.
Type
There is a type of compass called a safety compass that doesn’t have a sharp tip which can hurt someone. Instead of a sharp-pointed needle, it has a rubber tip.
It has a circle on one end, like a ruler, so you need to put a pencil into it (into the hole of the ruler’s arm) and draw around the center disc to draft an arc.
After a review of the compass and protractor, let’s move toward the distinctions between them.
Comparing a Protractor and a Compass
Although both are measuring instruments used to create arcs and calculate angles, they differ in certain aspects, which I will share with you.
Mechanism
Both can be served for a similar purpose but differ from each other.
A protractor like a full or half moon can be a semi-circle with 180 degrees or a full circle with 360 degrees. Although they have existed throughout history, modern protractors are made up of plastic.
The same goes for compasses; they are also around for ages consisting of two legs. One leg consists of a pointer, whereas the other has a clip to hold a pen or pencil.
Flexibility and Degrees
Standard protractors in the market consist of 180 degrees markings. To create a full circle, turn down the protractor or buy a complete circular one with 360 degrees.
In comparison, you can draw various circles of different diameters with a compass. Their size depends on where you set the midpoint and how big an angle it can draw with the pencil.
The flexibility of both instruments according to their purpose creates a vast disparity between them. Therefore, a compass is effective for making figures like arcs, or many kinds of circles, while a protractor is best for measuring angles.
Size Variations
A protractor’s size prevents it from measuring wider circles, but several specialized compasses have been employed to do just that. In this category, beam compasses are very much famous.
Trammel are points that can be fastened to a substantial wooden plank with brackets—makeup beam compasses. The other purpose of a beam compass can also be seen while decorating or cutting materials like wood, drywall, or stone. On the other hand, protractors lack this aptitude.
What is a Compass Rose?
The compass rose, also called a wind rose or star of a compass, is the directional figure which shows all four directions (north, south, east, and west).
The alignment of these cardinal directions on this figure allows you to read them easily. This compass rose shows their intermediate points on a map, nautical chart, or monument.
The cardinal directions are indicated with a compass needle that free spins. The South Pole of the compass is marked at one end of the red arrow, which points to the North Pole. This terminology makes it easier for people to navigate using the compass.
The phrase “compass rose” refers to the graduated markings on conventional magnetic compasses. Nowadays, practically all navigation systems such as GPS, NDB, nautical charts, etc., utilize a compass rose.
How Can You Use a Compass and a Protractor?
You can effectively use a compass or a protractor. However, you should be aware of how carefully you must handle these tools; so, let’s discuss how to use them properly.
Steps of Using a Compass
- To create neat and clean drawings, sharpen the pencil or file it using sandpaper.
- Using the compass, make a circle or an arc. Try not to pierce the paper when you carefully put the metallic point in the rough midpoint of a document.
- After that, grip this point firmly and rotate the compass by lowering its end.
- Form a complete circle by circling the edge with the pencil’s tip. Circles of varying diameters can be created by adjusting the compass’s legs.
- In some cases, gently tugging, pressing, or turning a little dial between the legs can bring the points closer together or farther apart.
Steps of Using a Protractor
- To draw various angles, use a protractor. Firstly, make a line with a ruler. Place a mark along this line somewhere.
- Protractors should be aligned with this line. Place the pencil on top of the zero line of the protractor.
- After that, mark along the protractor’s curve on the desired degree of angle. Then draw a line using the ruler from the mid of the protractor to where you created the mark. The distance between the baseline and this line is the given angle.
The above guidelines enable you to create the desired figures, angles, and arcs.
Bottom Line
- In geometry, engineering, and mechanics, particular tools are employed to produce beautiful and precise figures.
- The distinctions between two tools, a compass, and a protractor, are outlined in this post. Also this article states the best practices for applying them. Once you’ve mastered the fundamentals, you can use them for various tasks, such as drawing, dividing circles, and bisecting lines.
- A protractor is a measuring tool. Engineers use it to make engineering drawings in addition to measuring and drawing angles. It is constructed of glass or plastic.
- Another helpful tool for determining angles and circular shapes in geometry is a compass, a metal or plastic “V-shaped” tool.
- Protractors with 180-degree marks are the industry standard. Reduce the protractor’s angle or get a 360-degree complete circular to make a full circle. In contrast, a compass allows you to draw various circles with varying diameters.
- You can use both instruments to finish your job with accuracy.