Often you have to work with geometric figures, the calculations for which are not easy to explain. If you need to find the area of a square or rectangle, then you can conditionally divide them into some parts and intuitively derive the correct formula. However, the circumference is not quite a standard object for ordinary schoolchildren. Often there is a misunderstanding of this topic. Let's see what's going on.
The circle itself is formed due to two parameters: the radius and the geometric position of the center. The latter understands the senior classes, so he is of little interest to us. But the first sets the basic properties, such as area. The circumference actually depends only on the radius and is calculated using the following formula:
L=2RW
We take L as the desired indicator. The multiplier P ("Pi") is a constant. To successfully solve problems at school, it is enough to know that P \u003d 3.14. However, it is far from always necessary to substitute this value, since it is very simplified. If we are talking about large scales, then it is necessary to take into account a considerable number of decimal places. Therefore, in many cases, a general answer without any rounding is more acceptable. Remember that the calculation of the circumference of a circle depends only on the radius. This is an indication of howall points of the circle are far from the center. Accordingly, the larger this parameter, the longer the arc. Like normal distance indicators, L is measured in meters. R - radius.
In more realistic conditions, complicated tasks take place. For example, when the length of an arc of a circle is needed. Here the formula is a bit more complicated. It should be understood that it is based on the main pattern, but cuts off the part of the length that you do not need. In general, it can be written like this:
L=2PR/360n
As you can see, there is one new variable n. This is a visual indication. The entire circumference was divided into 360 degrees. Thus, it became known how many meters fall on 1 degree. Further, substituting the values of the desired rotation around the axis instead of the letter n, we will get the long-awaited answer. Taking a single segment, we proportionally increased it n times.
Why in real life do you need to know what the circumference is? This question cannot be answered in a way that covers all areas of application. But for the sake of familiarization, let's start with primitive watches. Knowing the radius of movement of the second hand, you can find the distance that it must cover in a minute. Once the path and time are known, we can find the speed at which it is moving. And then only people who work for hours will go deeper. If a cyclist is moving on a circular track, then his passing time depends on the speed and radius. You can also find its acceleration. In washing machines, it also cannot do without an indicator, which we have almost dismantled. There lengththe circle is necessary to count the revolutions (after all, everything rests on the distance) done in a certain amount of time. On a larger scale, circumference predicts planetary orbits and so on.
Thus, for a clear understanding of the topic, you need to remember only two formulas. This knowledge will be useful to you not only in school for good grades, but also in real life.
