We can calculate this problem according to the circumference formula of a circle.
1. The formula for the circumference of a circle is: C=2πr, where r is the radius and π is the pi. It is known that the radius of the circular cowshed is15m, and the cowshed is surrounded by three times, which means that the iron wire needs to circle the cowshed three times. Therefore, the required length of iron wire is: total length of iron wire = circumference × turns =2πr× turns.
By modifying the above formula, we can get: number of turns = total length of iron wire /2πr, then the length of iron wire needed to enclose the cowshed for three times is: total length of iron wire = number of turns of iron wire × 2π r = 3× 2π15 = 94.2m. ..
Formula of circle
The formula of circle mainly includes the formula of circle area, pi, radius and diameter, and the formula of sector area. These formulas are widely used in mathematics and physics.
First of all, the area formula of a circle S=πr? Or S=πd? Used to calculate the area of a circle. A change in radius or diameter usually leads to a proportional change in area.
Secondly, the formula of pi is that pi is equal to 3.141592653589793, which is a constant to indicate the ratio of the circumference to the diameter of a circle. In practical application, different π values can be adopted as needed.
In addition, the formula r=S/2 or d=S of the radius and diameter of a circle is used to determine the radius or diameter of a circle. Radius and diameter are the basic parameters of a circle, which can be used to calculate geometric quantities such as the area and perimeter of a circle.
In addition, the sector area corresponding to an arc is calculated by the sector area formula, and its ratio to the area of a circle is equal to the degree of the central angle corresponding to this arc. This formula is widely used in mathematics and physics, such as bicycle speedometer, electric fan speed and so on.
Cyclic formulas are widely used in mathematics, physics, engineering and other fields. For example, it is widely used in architectural design, machinery manufacturing, electronic products, transportation and so on. The application of these formulas can help us better understand and apply the basic geometric shape of a circle, and also help us solve practical problems. At the same time, the derivation process of these formulas is also the embodiment of deep understanding and application of mathematics and physics, which is helpful to improve our mathematics and physics literacy.