How the circle differs from the circumference: explanation. Circle and circle: examples, photos. Formula of the length of the circle and area of \u200b\u200bthe circle: Comparison

We understand what a circle and a circle are. The formula of the area of \u200b\u200bthe circle and the length of the circle.

Every day we find many objects in the form that form a circle or on the contrary a circle. Sometimes the question arises of what a circle is and how it differs from a circle. Of course, we all underwent geometry lessons, but sometimes it will not hurt to refresh knowledge with very simple explanations.

What is the length of the circle and the area of \u200b\u200bthe circle: definition

So, the circle is a closed curve line, which limits or, on the contrary, forms a circle. A prerequisite of a circle - it has a center and all points are equivalent from it. Simply put, a circle is a gymnastic hoop (or, as it is often called hula hoop) on a flat surface.

The length of the circumference is the total length of the very curve that forms a circle. As is known, regardless of the size of the circumference, the ratio of its diameter and length is equal to the number π \u003d 3.141592653589793238462643.

From this it follows that π \u003d l/d, where L is the length of the circle, and D is the diameter of the circle.

If you know the diameter, then the length can be found according to a simple formula: l \u003d π* D

If the radius is known: l \u003d 2 πr

We figured out what a circle is and we can move on to the definition of a circle.

A circle is a geometric figure that is surrounded by a circle. Or, a circle is a figure whose line consists of a large number of points of the figure equivalent from the center. The entire area that is inside the circle, including its center, is called a circle.

It is worth noting that at the circle and circle, which is located in it of the radius and diameter, the same. And the diameter, in turn, is twice as much as the radius.

The circle has an area on a plane that can be recognized using a simple formula:

S \u003d πr²

Where s is the area of \u200b\u200bthe circle, and R is the radius of this circle.

How the circle differs from the circumference: explanation

The main difference between a circle and a circle is that a circle is a geometric figure, and a circle is a closed curve. Also pay attention to the differences between the circle and the circle:

• The circle is a closed line, and the circle is the area inside this circle;
• A circle is a curve line on a plane, and a circle is a space closed into a ring with a circle;
• The similarity between the circle and the circle: radius and diameter;
• The circle and circles are a single center;
• If the space inside the circle is shared, it turns into a circle;
• The circle has a length, but the circle does not have it, and vice versa, the circle has an area that does not have a circle.

Circle and circle: examples, photos

For clarity, we suggest considering a photo on which on the left is a circle, and on the right a circle.

Formula of the length of the circle and area of \u200b\u200bthe circle: Comparison

Circular length formula l \u003d 2 πr

Circle Formula S \u003d πr²

Please note that in both formulas there is a radius and number π. It is recommended to learn these formulas by heart, since they are the simplest and will necessarily come in handy in everyday life and at work.

Circle area along the length of the circle: Formula

The formula of the area of \u200b\u200bthe circle can be calculated if only one value is known - the length of the circumference that borders on this circle.

S \u003d π (l/2π) \u003d l²/4π, where s is the area of \u200b\u200bthe circle, l is the length of the circle.

Video: what is a circle, circle and radius