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Showing posts with label mathematics application. Show all posts
Showing posts with label mathematics application. Show all posts

## 1.29.2022

### Squaring the circle

Squaring the circle. The solution of the problem. Almost accurate. Math draw.

 Squaring the circle. The solution of the problem. Almost accurate.

This construction is not a solution to the problem of squaring the circle, but it forced me to get my hands on the math and do all the verification calculations. If the correct solution should give a segment with a length of 1.77245 radii, then the length of the red segment in the figure is 1.78885 radii. A little more than necessary. How much more? The segment exceeds the required length by 0.9253% or by 0.01640 of the radius. The area of a square with sides equal to the length of this segment is 1.8592% greater than the area of a circle.

How to use it? For a friendly prank of math lovers. Build a square with sides equal to ten centimeters. Inscribe in a square a circle with a radius of 5 centimeters. Draw a line as shown in the figure and offer a ruler to measure the length of the resulting segment. It will be equal to 8.9 centimeters. Using a calculator, calculate the area of a circle, which is equal to 78.54 square centimeters. The area of a square with sides of 8.9 centimeters is 79.21 square centimeters. This discrepancy can be explained by the low accuracy of measurements using a ruler. Personally, after such rough calculations, I sat down to check the solution.

I don't recommend this kind of joke with my teachers or math teachers - they can force you to do all the verification calculations to refute this solution. The unsolvability of this problem was proved by the German mathematician Lindemann back in 1882. However, I have long been very distrustful of many proofs of mathematicians.

## 1.01.2022

### Signs greater than and less than

How to remember signs greater than and less than? A very long time ago, when I was little and went to school, the teacher taught us this. Even as an adult, I have always used this method.

We always do more with our right hand than with our left. If we bend our right arm at the elbow and raise it above our head, we get the "GREATER THAN" sign. We do less with our left hand. A bent and raised left hand will give us the "LESS THAN" sign. The elbow of the right hand points to the direction of the "GREATER THAN" sign. This is how it looks in the picture.

 Signs greater than and less than

Indeed, the arm bent at the elbow is very similar to the "greater than" and "less than" symbols. You don't even have to raise your hand. And this cheat sheet will always be with you. If mathematicians don't cut your hands off.

If you are left-handed and do more with your left hand than with your right? How then to be? You have two options. Or you think like everyone else and you won't have any problems with math. Or you write your "left-handed math" and learn a lot of interesting things.

## 5.15.2015

### The problem about the juice

On the Internet there are a lot of things. Yesterday I saw an interesting problem about the juice. I understand that the person made a mistake copying the text of the problem from the book. But it turned out very interesting. I used to see all over the math, just as I am translating the language of mathematics to the surrounding reality. That's how I read this problem and this is the decision I did.

A liter of grape juice is worth 6 manat. It was mixed with a liter of mulberry juice manat. A liter of juice sold for 10 manats. What benefits can be obtained from the sale of 10 liters of the mixed juice?

For those other than dollars knows nothing, to announce that manat - is the monetary unit of Azerbaijan (there is such a country). By the way, Muslims do not eat pork, mathematicians so do not use math-degree measure of angles in Calculus. As they say, find ten differences. It was the information for the overall development, but will return to the problem about the juice.

The number in the value of mulberry juice available. The man forgot to write. But mulberry juice can be stolen. Then it really does not cost anything. Such "schemes" are thriving in our lives. The lack of numbers in mathematics to denote the numeral zero. If we substitute the value of zero in mulberry juice, then the problem is easily solved.

For a start, we determine the number of cocktail, which is obtained by mixing two different juices. Each juice we take in the amount of one liter. If you do not like liters, take one gallon.

1 + 1 = 2 liters

Now we consider the cost of the resulting cocktail

6 + 0 = 6 manats

Calculate the cost per liter of cocktail

6: 2 = 3 manats

Who is the most interesting point - we determine the profit from the sale of a liter of cocktail

10 - 3 = 7 manats

At the end of the general view of the profits from this scam

10 * 7 = 70 manats

Conclusions:

1. With revenues of these scams is not to compare, but enough to start.
2. The juice can be diluted with water, then stealing nothing.

Disclaimer:

1. For the theft could be imprisoned.
2. For juice dilution with water can beat face.

If in the problem still listed price for mulberry juice, instead of the zero substitute that number. The solution of the problem will not change. Incidentally, the legal business from the business of the criminal also a little different.

## 4.21.2015

### Snail on a pole

Objective: Snail crawling on a pole height of 10 meters. During the day, she rises to 4 meters per night descends to 3 meters. For some time the snail reaches the top of the column?

 Snail on a pole

To solve this problem about a snail on a post need to revise some of its condition. The day the snail takes off the pole to a height of 4 meters. The post has a height of 10 meters. Reformulate the question: at what height should be a snail to a running start to fly to the top of the column? The answer to this question is easy to calculate:

10 - 4 = 6 meters

Now the second question: how many days should snail fidgeting up and down the pole to reach a height of 6 meters. Again, take the hands of the math and think:

6 / (4 - 3) = 6 days

As a result, we have six days cochlea will need to enter the starting position for a breakthrough victory, and one day for the race victory. The result is that the triumph of a snail on a post we will see after 7 days.

The same mathematical problem can be formulated with a modern twist. Look how it will sound in the Russian mathematical textbooks soon: From the border to Russia at the borders of NATO distance of 10 thousand kilometers. Green men move per day from the Russian border to NATO at the border at a distance of 4000 kilometers. During the night, NATO troops cast of unknown green men on the 3,000 kilometers back to Russia. How many days disappear NATO? The answer to this problem is the same: after 7 days of the great light of the Russian world illuminate the whole of Europe. By the way, the light of the Christian faith had once lit up Europe funeral pyres of the Inquisition. And the Third Reich sprawling across Europe recently. We must not forget history.

## 4.08.2015

### How not to change the signs inside the brackets?

All of us are taught to change signs when opening or closing brackets of the expression in brackets, if before the brackets minus sign. Let's look at this tedious process for half-dead examples.

11-(2+5-4) = 11-3 = 8

Before the expression in brackets is a minus sign, it means that the disclosure of the brackets need to change all the signs to the contrary all the numbers that are inside the parentheses. Consider the same example, but without the brackets.

11-(2+5-4) = 11-2-5+4 = 9-5+4 = 4+4 = 8

Now let's try to take a part of the expression in parentheses.

1+2+3+4 = 10

Naturally, you ask: "Where is the minus sign?!" Do not worry, now appear.

1+2-(-3-4) = 3-(-7) = 3+7 = 10

I put in front of the brackets and the minus sign to change the sign before the numbers inside the parentheses. In disclosing the brackets again I changed the sign, because before my braces a minus sign. In the end, the result remained unchanged.

Now a more complex example.

17-6+9 = 20
17-(6-9) = 17-(-3) = 17+3 = 20

As you can see, continuous headache turns out, when suddenly appears before the brackets the minus sign. How not to change the signs inside the brackets? Very simply - no need to put a minus in front of the brackets. Look how it's done.

17-6+9 = 17+(-6+9) = 17+(3) = 17+3 = 20

Now consider the last two examples under the microscope. In the first case I put the first parenthesis after the minus sign. I like a knife cut a negative number into two parts - a minus sign and a positive number. The minus sign was in front of the bracket, and a positive number - within the brackets. Look.

17-(6........

In fact, we are in parentheses conclude a positive number, which until then was negative. Changing the sign of the first number in parentheses passed on complete autopilot without our intervention. A sort of a machine circumcision minus sign in numbers. But with the other numbers that fall into these brackets are already having problems. Signs they need to be changed manually.

In the second case I put the opening bracket before the minus sign. In fact, I put in brackets a negative number with a minus sign. Here's how it looks initially.

17(-6.........

Now, between numbers 17 and bracket there is no sign that mathematics implies multiplication. But I do not have anything to multiply. To answer in the solution remained the same example, I set the bracket additional "plus" sign.

17+(-6.........

Now everything is correctly written. Before the parentheses appears the plus sign and signs before the numbers inside the brackets intact. No mathematical crime I did not commit, just competently get rid of extra action on the replacement characters inside the brackets. Why mathematics always do? They had not taught this. If it is not in the curriculum, and then teach you that no one will. Math enough to know, you need to also know how to use her.

## 4.14.2011

### Why are sines and cosines needed?

Why are sines and cosines needed? Really, interesting question. In comments to the trigonometric circle of sines and cosines such question appeared:

where will sin and cos be useful in life?
p.s why are they needed sines cosines?

Let us will call a spade a spade. To swingeing majority from you they will be never useful. Unless, when will your children go out into school and will begin to study trigonometric functions, they too will put question you "Why are sines and cosines needed?" and, in addition, will ask to explain, what is it.

Money we use every day already not alone thousand years and perfectly we do without every sines, cosines and other elegant mathematical pieces. I assure you, and through millions of years in the count of money nothing will change. Not because we are such dull, and because such are mathematical properties of money : it is impossible to increase roubles on roubles and with money in the second degree to hurry in a motor show to buy "Lamborghini".

On a kitchen, in culinary recipes, you will meet neither sines nor cosines too. If to give a glance soberly on our everyday life, then all our everyday mathematics remains somewhere at the level of knowledge of Ancient Greece. We are enough with a head.

So why are sines and cosines needed? As compared to Ancient Greece, we have very much different pieces about that ancient Greeks could not dream even today. Even their Gods did not ride on machines, did not use mobile communication, did not communicate on the Internet. But we have all of it and we use this constantly. Did all this extraordinary riches undertake from where? He was created by us. At first scientists did the scientific opening. Then engineers, on the basis of done by the scientists of opening, created every useful things. We use these things today, not having not the least concept about that is into these things and what scientific laws are fixed in basis of their work. So, if there were not sines and cosines, there would not be all these useful things.

Sines and cosines are used most effectively scientists and engineers. I will not say that they continuously trigonometric functions are used only. No, they use them rarely, but well-aimed. Sines and cosines often are in the formulas of different calculations an engineer or scientific.

Often with sines and cosines it is necessary to clash to the geodesists. They have the special instruments for an exact goniometry. Through sines and cosines corners can be converted into lengths or coordinates of points on an earth surface.

The teachers of mathematics on the sort of the duties constantly deal with trigonometric functions. This year they told about sines and cosines to you, the next year the teachers of mathematics will tell the same to other students. Such for them work - to teach.

Schoolchildren and students study trigonometric functions on the lessons of mathematics. Personally I got through tortures sines and cosines at school, техникуме, institute.

Adults sometimes engage in sines and cosines then, when their toschoolchildren need a help at preparation of homeworks.

All! Sines and cosines do not need other generally! In everyday life most people they are not used hardly ever. If I wrong, remedy me.

So why then generally to teach these sines and cosines? Well, firstly, such is the school program. Secondly, if you in life may need apply a sine or cosine, you know already, what is it and where it is needed to search information about them. The knowledge gained at school will fully have you, what is independent in everything to understand.

So what such the sines, cosines and other trigonometric functions? It is a mathematical instrument it is needed that to be able to use. That we this instrument we do not use hardly ever, talks not that studying them is not necessary, and that efficiency of application of the knowledge gained by us is practically equal to the zero. But it is quite another theme already.

## 3.11.2011

### Four-valued mathematical tables for blondes

Four-valued mathematical tables of Bradis - this was the basic mathematical reference book of soviet schoolchildren, students, engineers to appearance of calculators.

A trigonometric table for blondes is done by me to the navigation more informatively saturated in a plan. It what you did not lose way and did not entangle trigonometric functions.

Trigonometric table of sines and cosines
- from 0 to 90 degrees punctually to the minute corner.

Trigonometric table tangent cotangent in degrees - from 0 to 90 degrees punctually to the minute corner.

Trigonometric table in radians - sin, cos, tan.

We will do justice to work of Bradis and we will remember a bit history. His book "Tables of the four-valued logarithms and natural trigonometric sizes" went out in 1921. This book was repeatedly reprinted, but already under more simple name "The Four-valued mathematical tables". This bestseller looked approximately so.

It is possible to say without a false modesty, that on these tables all Soviet Union was built, a man started to fly in space, a soviet nuclear club was created et cetera. Schoolchildren, engineers, scientists - all used the tables of Bradis. We will remember those distant times - the Internet is not present, mobile telephones are not present, computers and calculators are not present. Even televisions were not then! There were only books. In many books formulas were written for a calculation, and necessary for calculations numerical values were taken from the tables of Bradis. And what did numbers multiply by then? Not on accounts... Well and time was! As it was then possible normally to live??? But lived somehow.

An interesting question arises up. What mathematical tables did Americans build famous sky-scrapers on and created the nuclear club? In fact did not they steal for us tables of Bradis? Omniscient Wikipedia is quiet on this occasion, and information about the table of Bradis in Wikipedia in English language I did not find. There is there a mathematical reference book of Abramowitz, Milton and Irene A. Stegun with tables, but he is published was only in 1964. And that did Americans have to these tables?

I used the table of Bradis once. This whole art, to search the value of trigonometric functions punctually to the minute corner. Fortunately, today we have calculators.

Unfortunately, work of great soviet writer of mathematical tables Bradis me does not interest. Therefore the four-valued mathematical table into language of blondes transferred will not be. In the simplified kind the table of Bradis will be presented in the tables of sine, cosine, tangent and cotangent.

## 2.08.2011

### We do repair

Blondes sometimes too do repair. Here again without mathematics application it is impossible to manage in any way. It is necessary to pay For repair money. Thus inevitably there is a question: how many and for what from me take money? Whether correctly builders have counted repair cost? How to count amounts of works at apartment repair? Here, as it is impossible by the way, knowledge of mathematics will be useful to you. And so, if we do repair it is necessary to know volumes of forthcoming works approximately at least. Calculation of amounts of works - business tiresome enough, but necessary. How many it is necessary to buy wall-paper? How many it is necessary to buy a tile? These figures as undertake from amounts of works.

Amounts of works are considered very simply, basically, on the rectangle area - the length is multiplied for the width and the area (in full conformity with the multiplication table) turns out. If it is a floor - that the length and width of a room undertake. Measurements are spent by a roulette between opposite walls over a plinth. As the measuring tool it is possible to use metre by which you measure volume of hips, waists, breasts. For example, if at us a room in the size 5,0 on 3,0 metres, in this room of 15 metres of a square floor.

5 · 3 = 15

It is amount of works on packing of a tile, a laminate, linoleum, the device of a coupler, a floor first coat and so forth in this room. In addition the floor area in a doorway and радиаторной to a niche can be considered. This area increases to area already received by us. By builders at estimate calculation factors of complexity of works can be applied, but masters should prove that work is executed not the standard. For example, in a bathroom the tile of two colours was killed on a curve that, naturally, more difficultly, than simply to put a tile. Even for selection of drawing of a tile cost of works can be increased.

If the room has the difficult form then the floor area is calculated on the areas of simple geometrical figures into which it is necessary to break mentally a room and for which you know formulas of a finding of the areas. In the practice I very often used the formula of Gerona for a finding of the area of a triangle on length of three parties.

If any works are regarded in running metres (for example, plinth installation) then it is simply measured by metre or a roulette on room perimetre. In a room in the size 5 on 3 metres the perimetre makes 16 metres running.

(5 + 3) · 2 = 16

For calculation of quantity of a plinth it is necessary to take away width of a doorway, usually 0,8 - 0,9 metres, to add a plinth on door slopes (if in a room it is). Let in our case the door will be 0,9 metres, and the door slope will be in the width 0,3 metres. Total we will receive 15,7 metres running plinth installations.

16 - 0,9 + 0,3 · 2 = 15,7

If any works are regarded for a piece (installation of corners on a plinth, installation of sockets, etc.) It is counted up at random by a finger in a product. Two times and too the product is not considered one. It is necessary to mean that installation box for setting of electric wall outlet and socket installation are different works which are paid for different quotations though are carried out consistently in one place. By the way, boxes for setting of electric wall outlets are established and for switches. Check is carried out simply: quantity of switches plus quantity of sockets to equally quantity box for setting of electric wall outlet. If figures do not converge, then is considered at random by a finger of the builder (already the builder should count all at your presence) and listened its arguments, after all situations happen different (the telephone socket, the television socket, the computer socket - all of them are put in box for setting of electric wall outlet). box for setting of electric wall outlet is cheaper than an assembly box and it can be used in junctions of wires - such beggar an European-quality repair variant.

The ceiling area is considered in the same way, as well as the floor area - the sizes from a wall to a wall are measured. The area of niches increases, and the area of columns is subtracted from the ceiling area. Usually the ceiling area is equal or less areas of a floor (remember, in the floor area the area in doorways, radiator niches can be added).

The area of walls is considered multiplication walls on height of a room minus the area of door and window apertures are long. Let at us height of a room of 2,5 metres, a window in the size 1,4 on 1,5 (height) of metres, a door 0,9 on 2,1 (height) of metres. Then the area of walls is equal to room perimetre (we already so considered a plinth) increased by height of a room minus the area of apertures about makes 36,0 metres square:

((5 + 3) · 2) · 2,5 - 1,4 · 1,5 - 0,9 · 2,1 = 16 · 2,5 - 2,1 - 1,9 = 40 - 4,0 = 36

Furnish of slopes is considered, usually, in running metres. The window slope in our case makes 4,4 metres of the running:

1,5 · 2 + 1,4 = 4,4

The door slope equals 5,1 metres of the running:

2,1 · 2 + 0,9 = 5,1

If the quotation for slopes in square metres then the received running metres it is multiplied separately: length of a window slope running metres for width of a window slope, length of a door slope for width of a door slope. If in a room the oil panel in height of 1,8 m then the panel area is calculated separately is executed and it equals of 25,6 metres of the square:

((5 + 3) · 2) · 1,8 - 1,4 · 1,0 - 0,9 · 1,8 = 28,8 - 1,4 - 1,6 = 25,6

Here for a window of 1,0 metres is a distance from a window sill to top of the oil panel. The area of furnish of walls over the oil panel makes remained from a total area of walls of the square of 10,4 metres:

36 - 25,6 = 10,4

The areas in other premises are considered precisely also. More simple method still nobody has thought up. Write down the calculations in a writing-book on each room separately and summary calculation on apartment - separately: циферка in циферку with all signs on mathematical actions. The error in calculations can be the most banal - on the calculator not that key have pressed at calculation of addition, multiplication, subtraction. From builders you in the right to demand explanations concerning the overestimated amounts of works. In disputable cases in common make the necessary gaugings and together do calculations - here you quickly find out, who and where exactly was mistaken.

You can compare quotations of builders to the quotations presented in my building catalogue. Usually the highest quotations for civil work - in Moscow.