Connect a right angle with a segment. Measurements and construction of angles when carrying out various works. Golden Egyptian Triangle
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A right angle between walls is necessary quite often. For example, to correctly install a bathtub, kitchen sink or table. But most people simply do not take this need into account, and then regret it when a centimeter gap appears between the bathtub and the wall. Also, an indirect angle is revealed by floor tiles when the cutting on the sides is different. And there are even worse situations. Therefore, take this material seriously. Builders erecting modern houses
, contrary to the opinion of the majority, they do not care about the proximity of the corners in apartments to 90 degrees. All they care about is the amount of work, and often they are not even given any measuring equipment. Just a trowel and a trowel. “Way, Rovshan!”
How to make a right angle between the walls after such a hack? There are two options here: either we plaster on the beacons, or we level the walls with plasterboard. And if in the second case no difficulties should arise - we just twist the profiles along the square, then everything is a little more complicated. By the way, the option “I’ll level everything with tiles” won’t work either. Practice shows that all those who try to make a right angle by smoothly building up a layer of tile adhesive invariably mess up. Moreover, their angle is not straight, and the tiles lie crooked. If you find the strength and courage to plaster on beacons, then you can make a perfect right angle without any problems. On which you can quite calmly lay the tiles “under the comb”. First fundamental principle
plaster at a right angle - first we plaster one wall in the usual way.
Usually the longest. Entirely. It is much easier and faster to build an angle from a finished plane.
What's next? You will need two plastering rules. Preferably the length of the entire wall. Often bathrooms have dimensions around 175x175, so in this case, take two two-room apartments and shorten them with a grinder or a hacksaw. Let's assume that you have already plastered one wall, ideally. And the adjacent one has dimensions of 175x275 cm. In this case, two beacons will be needed. Let's mark them. Everything is as it should be, at a distance of 30 cm from the walls. But there's one here. The pair of lower screws must be strictly at the same level. Accordingly, the top pair too. A little later you will find out why. It is also recommended to mark a line on the plastered wall that lies at the same level as the bottom pair of screws.
Next, holes are drilled and dowels and screws are driven into them. Now what? Of course, you can’t do anything with a simple half-meter square. The solution lies on the surface - you need a larger square. It is made from two rules. But how to make sure that they form a strictly 90 degree angle? Not on a small square, that makes no sense. Everything is much simpler.
There is the Pythagorean theorem. Which unambiguously establishes the ratio of the sides of a right triangle. Root of the sum of squares of the legs equal to the hypotenuse. Remember your school geometry course. What this all means is that if you can build a triangle on the floor whose sides are related in the same way, one of its angles will be exactly 90 degrees. The simplest case is the so-called. Egyptian triangle, whose sides are in a ratio of 3:4:5. It is usually convenient to take 120:160:200 cm in practice.
So, a line is drawn on the floor with a pencil. It is not advisable to use a marker; accuracy is important here. Two points are placed on it: one at the edge, the second at a distance of 120 cm from the first. Then take a piece of the lighthouse, or you can use a tape measure. It will be necessary to set aside 160 cm from the first point, and 200 cm from the second. It would be more precise to construct fragments of circles of the indicated radii. The intersection point of these figures will be the third vertex of the triangle. All that remains is to connect the vertices. That's it, you have constructed a right triangle with high accuracy. 
The next step is to place two rules on the floor exactly along the lines. Since they will lie with their beveled edges facing outward, this will not be so easy. You'll have to use a square. So, the rules are combined with the lines: 
Now you need to securely fasten them together. This is usually done with self-tapping screws with a press washer or black metal screws. The main thing is to prevent the rules from shifting relative to the lines under the influence of vibration from a screwdriver or drill. It is enough to consolidate the rules at two points:
But, in general, this is not enough. You need to use an additional strip from a Knauf protective corner, for example. We fasten it as shown in the figure: 
Now you have a huge, hard, and most importantly, accurate square. You return to the room where you will have beacons. There is already a line marked along which you will apply the square. Yes, you need to place it strictly in a horizontal plane, otherwise there will be an error.
You should have already previously assessed the degree of deviation of the angle from 90 degrees, so you know which screw from the bottom pair to take as a basis. Let's assume that the angle was obtuse, so the screw closest to the already plastered wall is unscrewed to a minimum (7-8 mm). And the far one will already twist around the square. Apply it to the line on the already finished wall and to the exposed screw of the bottom pair on the marked one. Look. Let's say the farthest self-tapping screw does not reach the square by about 4 mm. Unscrew it approximately this distance and again assess the situation with a square. You may have to apply it several times, but, in general, the installation process of the self-tapping screw will take you no more than a couple of minutes. If the angle was initially sharp, install the farthest self-tapping screw first. And the neighbor - along the square.
It is inconvenient to set the top pair of screws with the same square - it is heavy, it is difficult to lift it, it constantly slides off the heads. Therefore, it will be easier to simply set them vertically relative to the bottom pair. By plumb line or bubble level. In any case, if your first wall is perfectly aligned, you will get a perfectly right angle both above and below, automatically.
If you need to set a right angle on the opposite wall, then no problem, do everything exactly the same. This may be necessary, for example, if the dimensions of the bathtub are close to the walls. At the same time, cutting the tiles on the floor will work out perfectly. It is recommended not to place all the beacons in advance and then plaster them. It would be much better, although it would take longer, to mark and plaster each wall one at a time. But you will know for sure that you have not made a mistake anywhere.
Now you know how to make a right angle between walls when plastering. By spending a couple of hours marking, you will save more on laying tiles, and get professional quality it will be much easier.
Jun 6, 2014 ADMIN
Before you learn how to construct a right angle, you need to remember its definition. A right angle is an angle of ninety degrees formed by two perpendicular lines. You can also say that it is half a full angle. There are several ways to build right angle.
Methods for constructing a right angle
The simplest thing is to construct a right angle using a drawing square. It is applied to the paper and lines are drawn along the perpendicular sides: a right angle is obtained. You can also use a protractor. Attach a protractor to the line drawn with a pencil and mark a ninety-degree angle on paper. Then connect this mark with a line (along a ruler) to a line on the paper.
- There is a method for constructing a right angle using a compass and ruler. First you need to draw a circle with a compass and draw its diameter. Then mark an arbitrary point on the circle and connect it to the ends of the diameter: you get a triangle inscribed in the circle. Its angle (with its vertex at a point on the circle) will be right.
- The second way is to draw any two intersecting circles. Connect two intersection points with one line, and draw the other through the centers of the circles. These two segments will intersect at an angle of 90 degrees.
- If you don't have drawing tools, you can use any rectangular objects. This can be a sheet of cardboard, any packaging (medicine, a pack of cigarettes, a box of chocolates, etc.), a book, a photo frame, etc.
Constructing right angles on the ground
In general, constructing right angles on the ground is necessary in construction, when dividing plots of land, etc. For this purpose, special instruments are used - eker, astrolabe, theodolite. But it is unlikely that these tools will be, for example, on summer cottage. Then you can use a method that has been used since ancient times. You will need three pegs and ropes of 3, 4 and 5 meters. Stick a peg into the ground, tie 3 and 4 meter ropes to it, and the rest of the stakes to their ends. Connect the last two pegs with a 5-meter rope, pull the resulting triangle, and drive these stakes into the ground. The angle of the triangle with the first peg will be right.
As you can see, there are many simple ways to construct a right angle.
A construction tape measure for an electrician is as essential a tool as a voltage indicator. Even those professionals who have axle builders and laser rangefinders in their tool kits always have an ordinary tape measure in their pouch.
You can’t do without it either when marking electrical wiring routes or when installing socket boxes.
However, not everyone is familiar with all the secrets and additional features when using a construction tape measure.
It turns out she has a lot hidden abilities, which will help you replace several tools at once and significantly save time on repairs.
By the way, one of the important tips for those who use cheap Chinese tape measures is the following - if you have just such a copy, then try to take all measurements with one tape measure.
The same size may not match when measured with different tape measures.
One friend measured the distance of walls in a house with a Chinese tool, and in a store he used their tape measure when buying materials. As a result, at home I was very surprised by the result of the purchase.
Movable hook on roulette
A movable hook is found on almost every roulette today. And this thing is not at all for conveniently scratching your back :) 
Beginners generally often think that this is some kind of marriage. What will be the final accuracy if one of the key elements is loose and not securely fastened? Some even manage to rivet it immediately after purchase.
It turns out that a movable hook is a necessity, without which normal work is not possible at all.
This is explained by the fact that measurements with a tape measure can be made in two ways:
When you measure distance from an object, the toe acts as a zero point. When measuring with the grip of an object, the grip extends to its thickness. Thus, the zero mark again coincides with the edge of the object.
In this case, the measurement accuracy does not suffer, but rather is maintained.
However, a fair remark should be made - the movable hook breaks over time and an error of up to a couple of millimeters may appear.
This happens due to the constant impact of the hook when closing.
Therefore, you should not wind up the construction tape with a spectacular click at the end, thereby you will only shorten its service life.
In many more models, the tape measure has a hole at the very beginning at a distance of 2.5 cm. 
It was made for a reason, but again to make your work easier alone.
When there is nothing to fasten to with a hook or it is inconvenient to use it due to the oblique surface, use a simple awl or nail to firmly secure the tape through the hole and stretch it to any length.
By using such a hole in the tape measure, you will not have to use similar grips as in the photo below. 
And all the marking work can be easily done without a partner.
Measurements in openings and corners
As you understand when measuring in corners, it is very difficult for the middle of the tape measure to reach directly into the corner. It is also inconvenient to take precise measurements in a door or window opening. 
Therefore, when you need to measure an opening, use the body as an extension of the tape measure. 
On outside The tape measure itself indicates the size of the case, which must be added to the tape readings when measuring. 
If this size is not marked on the body, no one is stopping you from measuring it yourself and writing it in any convenient place.
There is another way to make similar measurements using masking tape. Place a piece of tape on the surface and take two measurements in opposite directions.
In this case, it is better to use a pencil to mark ticks rather than simple dashes. They will visually show the mark more accurately. Whereas the line may be drawn crookedly, which will cause an error. 
After taking two measurements, you need to add the results and get the exact size.
Hole in the toe
On many holds, the tape measure has a small hole. This hole is convenient for hooking onto a screw or nail. After this, the hook will not jump off anywhere. 
This is especially useful when you are taking measurements alone over long distances. The measurement error will be no more than 1-2mm, since the center of the screw is almost at the zero mark of the tape. 
This connector in the hook also makes it very convenient to draw circles. You don't need to have a compass or protractor with you.
In some models, the hooks are made magnetic. 
In addition to their direct purpose, such hooks are convenient for lifting fallen objects without getting off the stepladder. 
Roulette marker
With a little modification to a cheap tape measure, one tool makes an excellent marking tool.
Take the leg of the compass, which is used with with simple pencils, and secure it to the outside of the tape measure. 
This design can be made removable, or even adapted for a separate tape measure. 
This device is very convenient for making various marks or using it as a surface thicknesser. 
And when using a screw, circles of the desired diameter are easily drawn. 
If you're working with drywall or other surfaces that can be safely scratched, then the tape measure may be worth repurposing for another possibility. Use a file to make notches on the toe. 
After which, using this hook, marks are easily made on the surface. In this case, it is no longer even necessary to have a pencil at hand. 
Roulette reminder
The outer part of the tape measure can be easily turned into a mini reminder or writing surface. Take masking tape and stick it on the side of the tape measure. 
If you don’t have a paintbrush at hand, you can write directly on the body itself.
True, to do this, you first need to go over the surface with sandpaper. 
This way you will make it somewhat velvety, after which the inscriptions will be applied much easier. 
Of course, you need to write with a pencil, after which all this can be easily erased with an eraser.
Roulette calculator
With the help of a construction tape, it is very easy to divide any number in half with an accuracy of up to a millimeter, without resorting to a calculator.
Take the size on the tape measure, for example 116cm - and fold the tape in half and align the zero mark with it, where the top hook is.
Exactly at the point of inflection the required result will be - 58cm. 
In the same way you can not only divide, but also subtract. For example, the total length of your wall is 2m 11cm, and the junction box is located from the first edge at a distance of 1m 38cm. You need to quickly find out how much is left from this junction box to the other edge of the wall in order to measure the cable channel.
Pull the tape out 2m 11cm and fold it in half. 
Then look for the 1m 38cm mark. Just opposite it, on the second half of the tape, the distance you need will be shown - 73cm. 
Dividing into several parts with a tape measure
Using an ordinary tape measure, you can easily divide the work surface or workpiece into the required amount equal parts. This method is suitable primarily for large surfaces - it will not work for pipes or cable ducts.
What do you usually do? Measure the total length or width, then do the calculations and divide the distance by required quantity parts. Then again measure these parts on the surface with a ruler or tape measure. 
It turns out that all this can be done without a calculator and even without calculations. Take a number on the tape measure that is greater than the width of the workpiece, and at the same time a multiple of the value by which you want to divide the distance.
For example, the width of the board is 17cm, and you need to divide it into four equal parts. Move the tape measure diagonally to the nearest 20cm mark. Then easily divide these 20cm by 4 and mark marks at distances of 5cm, 10cm, 15cm, 20cm. 
As a result, you have divided the surface into the required number of parts with just one movement of the tape measure. 
They wanted to divide it into 6 parts - nothing complicated. You can move the diagonal up to 30cm and do the same.
You can also use a tape measure to accurately measure the cross section on a round pipe. To do this, press the tape tightly around the perimeter of the pipe, aligning the ends. If you align it exactly, it will not lie at any other than an angle of 90 degrees.
The wider the tape measure, the better. You can do the same trick with a simple piece of paper. 
When it is impossible to measure the diameter of a pipe or workpiece from the end, construction tape and geometry will again help. Wrap the tape around the pipe and measure its circumference. After which the result must be divided by Pi = 3.14. This will be the required diameter.
Once again using knowledge of geometry, using a construction tape without squares and other tools, you can check the accuracy of the right angle. As you know from school course- the sum of the squares of the legs of a right triangle is equal to the square of the hypotenuse. 
Take any surface where there should be a right angle, for example two walls of a room. Use a tape measure to measure 30cm in one direction and 40cm in the other and put marks. If the angle is really right and the builders didn’t screw up, then by connecting these two marks along the hypotenuse, you should get a distance of exactly 50 cm on the tape measure.
Each of us went to school. There a man gets great amount the knowledge that may later be needed in life. Not everyone, of course, can fully appreciate the significance of the knowledge acquired at school, but this is not the point now.
Mathematics. This is a scary word for many., which frightened quite a number of schoolchildren at one time. Numbers, formulas and calculations were amenable to only the most inquisitive. And every year this complex subject became more and more difficult.
In high school, geometry appears and everything becomes even more complicated and incomprehensible. Perhaps many at least once in their lives, but in their hearts, cursed a science they did not understand and wondered why it was needed at all, and whether it would be needed in life.
Perhaps in Everyday life It was not possible to apply the knowledge acquired at school. It was hardly necessary in the middle broad daylight calculate logarithms and quadratic equations or prove that two parallel ones will never converge. But where knowledge of geometry and mathematics may certainly be needed is in construction and when carrying out repairs.
This article will focus on calculating the right angle, which is required during the construction of buildings. Precision in building construction must be complied with, because only accurate calculations can eliminate distortions and instability in the organization of the entire building. Calculating a right angle during construction is not such a difficult process, which will require knowledge and application of some simple rules mathematics and geometry. This will be discussed in more detail below.
Is it really a right angle?
Perhaps some readers who read the title of this article will object that a right angle cannot always be obtained, and even and precise right angles are not always used in construction.
And, in principle, they are right. It is very difficult to obtain, especially if there is unevenness in the foundation on which the building is being constructed. But even taking this into account, under no circumstances can one conclude that the calculation of a right angle can be done simply “by eye”. In any case, if it is not possible to calculate the ideal right angle, then it is necessary to achieve the closest value to the ideal angle of 90 degrees. And this can be achieved using simple tools and not the most complex mathematical knowledge and knowledge of geometry.
What is needed to determine a right angle?
So, what tools will you need to use to check the right angle? It’s worth noting right away that no equipment or serious tools are required for this. You will need to use very simple things that can be found in almost every household. And even if you don’t have them on hand, you can easily purchase them in the store. There will be no difficulties with this.
To calculate a right angle you need to take:
- Pencil;
- Construction tape.
That's all. It's that simple.
How can you calculate a right angle?
So, this article will describe the 3-4-5 principle when determining a 90 degree angle. There is nothing complicated about it. You just need to think a little and delve into all the calculations that can help in checking the angle.
So, the following steps need to be outlined:
Conclusion
Here's how easy it is to calculate a right angle without using any construction tools or instruments. You can use the simplest, but at the same time very effective remedy, which, coupled with the use of existing knowledge and simple calculations, can help make measurements.
When using the suggested values, the key is the final measurement between the two marks that were made earlier. The distance, which will be exactly 5 meters, will seem to be straight. If the value is more or less than 5 meters, this will mean that it is not straight.