What tool is used to mark lines at right angles?

Answer 1

Names of Tools Used to Measure Angles

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While many may think of angles only in terms of geometry, angles occur in most everything. We recline our car seat to a comfortable angle. We adjust our Computer Monitors to angle them so we can see the screen easier. Architecture uses more than 90-degree angles; it also uses other aesthetic angles to create more interesting buildings. Art uses angles in all media. Angles can be used to calculate heights and locations. Angles are everywhere. As such, we have special instruments to measure angles.

1. The Protractor

   • The protractor is the most basic tool for measuring angles. It is used in math applications from engineering to architecture. The most common protractor is a half-circle with degrees marked from 0 to 180. Most protractors mark degrees in both directions, creating a double row of numbers. So it is important to assess whether the angle is smaller or larger than 90 degrees (a right angle) before deciding which row of numbers to use. Full circle, round protractors can also be found, which will be marked up to 360 degrees. Bevel Protractors have swinging arms to help measure the angle. Because these types of protractors have moving parts, they are classified as mechanical protractors.

   Navigational Plotter

   • Aviators use a navigational plotter to help plot their course. A typical navigational plotter looks much like an ordinary plotter attached to the top of a ruler. A fixed plotter has the half-circle protractor directly over the ruler, while a rotating plotter uses a circle (or round) protractor attached to the ruler. Because aviators use both statue (standard) miles and nautical miles for their measurements, plotters typically have both scales on them. The pilot places the hole in the protractor base of the plotter over a longitude line and then angles the ruler along the flight course marked on a sectional. The pilot can read the true course where the longitude line intersects the protractor (or plotter's azimuth).

   The Sextant

   • Sextant is Latin for one sixth. The instrument's scale measures 60 degrees, or one sixth of a circle. Sextants have been used by navigators at sea for centuries. The instrument measures the altitude of a celestial object, such as the sun, above the horizon. Navigators use this angle along with the time of day (or night) to calculate their position line on a nautical chart. Commonly, sailors calculated their latitude by sighting (measuring with the sextant) the sun at noon. The sextant could also be laid on its side and used horizontally against charts to measure angles, such as the angle between two objects. Using it this way, navigators were able to calculate their position.

   The Theodolite

   • A theodolite is a field instrument used by surveyors, generally set up on a tripod for stability. It is composed of a movable telescope mounted within two axes, a horizontal axis and a perpendicular vertical axis. They are used to determine line of sight and for measuring the angles between survey marks. They accurately measure both vertical and horizontal angles down to arc seconds and are particularly useful when measuring inaccessible ground. While theodolites are key for engineering and surveying, they have also been adapted for use by other fields, such as meteorology and rocket launch technology.

   Miter Saw

   • Builders use the miter saw (also spelled "mitre" saw) for making angled cuts in wood. Because the saw's angle-measuring component resembles a box, the saw is also called a miter box. The wood is held against a straight piece, called the fence. The miter saw's blade (usually a circular blade) cuts at an angle to the fence, making a vertical cut. This angle can be adjusted by one degree increments. There are usually "stops" built into the box at commonly cut angles, such as 45 degrees. At the standard position, the miter saw makes a 90 degree cut. A compound miter saw also allows for angle changes to be made in cutting on the horizontal plane. This can be used to make beveled cuts. A slide allows the saw to make cuts longer than the blade's diameter. When the latter two features are combined, the saw is called a sliding compound miter saw.