The method of calculating the area of a circle, the method of calculating the area of a circle is th

The area of the circle is equal to the square of the radius multiplied by one-half of the diameter.

The formula for the area of a circle is: s= r, s= (d 2), d is the diameter, r is the radius, is the pi, usually taken, the formula of the area of the circle is constantly deduced by ancient mathematicians.

Zu Chongzhi, an ancient mathematician in China, started from the regular hexagon inside the circle, multiplied the number of sides, and used the area of the circle to approximate the area of the circle with the regular polygon.

The ancient Greek mathematicians started from the circle with regular polygons and tangent regular polygons at the same time, increasing the number of their sides, and approximating the area of the circle from both the inside and outside.

Mathematicians in ancient India used a method similar to cutting a watermelon, cutting a circle into many small petals, and then docking these small petals into a rectangle, and replacing the area of the circle with the area of the rectangle.

Kepler, a German astronomer in the 16th century, divided the circle into many small sectors; The difference is that he begins by dividing the circle into infinitely many small fan-shapes. The area of the circle is equal to the sum of the areas of an infinite number of small sectors, so in the last formula, the sum of the small arcs of the segments is the circumference of the circle 2 r, so there is s= r.

1. The area of the semicircle: s semicircle = (r 2) 2. (r is the radius).

2. The area of the ring: S big circle - S small circle = (r 2-r 2) (r is the radius of the large circle, r is the radius of the small circle).

3. The circumference of the circle: c=2 r or c=d. (d is the diameter, r is the radius).

4. The circumference of the semicircle: d+(d) 2 or d+ r. (d is the diameter, r is the radius).

5. The length of the arc of the sector l=the central angle (radian system) r= n r 180. ( is the central angle of the circle) (r is the radius of the fan).

6. Sector area s=n r 360=lr 2. (l is the arc length of the fan).

7. The radius of the bottom surface of the cone r=nr 360. (r is the base radius) (n is the central angle).

is the sum of an infinite number of small sector areas, so in the last formula, the sum of the small arcs of the segments is the circumference of the circle 2 r, so there is s = r.

The area of the circle is based onAxiom: "The area of the circle is deformed by softening equal area."(Circle to Square).is seven-ninths of the area of its inscribed square.", launchedTheorem:"The area of a circle s is equal to seven times the square of one-third of its diameter d"Area formula for a circle:

s=7(d/3)²。

Circle areaThe simplest formula for the calculation method:PiMultiply by the square of the radius.

The area of a circle refers to the size of the plane space occupied by a circle, which is often represented by s. A circle is a regular flat geometric figure.

There are many ways to calculate it.

Formula: Pi multiplied by the square of the radius.

It can be expressed with letters as: s = r2 or s = d 2)2. ( for pi, r for radius, d for diameter).

The area of the circle. Radius Radius.

Circumference of the circle = diameter = radius 2.

The process of deriving the formula for the area of a circle

Circumference. c): The diameter of the circle (d), the circumference of the circle (c) divided by the diameter of the circle (d) is equal to , then the meaning of multiplication is equal to the diameter of the multiplication circle (d) is equal to the circumference of the circle (c), c = d.

The diameter of the same circle (d) is twice the radius of the circle (r), so the circumference of the circle (c) is equal to 2 times times the radius of the circle (r), c = 2 r.

By dividing the circle into equal parts, you can put together an approximate rectangle. The width of the rectangle is equal to the radius of the circle (r), and the length of the rectangle is half the circumference of the circle (c). The area of the rectangle is ab, and the area of the circle is:

The square of the radius (r) of the circle is multiplied by , s= r2.

s=πr_The formula for the area of a circle is: s= r. where s denotes the area of the circle; For pi, it is an infinite non-cyclic decimal, generally without special requirements, in the case of calculation; r is the radius of the circle.

For example, if a circle has a radius of 2 centimeters, then the area of the circle is multiplied by 2 squares, and the area of the circle is calculated to be square centimeters. Kepler also imitated the method of cutting watermelons, dividing the circle into many small fans;

The difference is that he begins by dividing the circle into infinitely many small fan-shapes. The area of the circle is equal to the sum of the areas of an infinite number of small sectors, so in the last formula, the sum of the small arcs of the segments is the circumference of the circle 2 r, which is the familiar formula for the circumference of the circle.

To know the radius of the circle, the area of the circle can only be calculated if the radius of the circle is known; Then there is the formula for calculating the area of the circle: radius radius (pi) = area of the circle; Circle. The circular area formula is a theorem law.

is the square of pi * radius, which can be expressed in letters as: s= r2 or s= *d 2)2.

Prepare a piece of paper, a pen, a ruler and a compass, take out the paper and compass, place the compass in the middle of the paper, and hold it to draw the circle. The point of the compass is the center of the circle, and the circle is divided into several parts, which can be put together into an approximate rectangle.

The width of the rectangle is equal to the radius r of the circle, the length is half of the circumference c of the circle, the area is ab, the area of the circle is the square of the radius r of the circle multiplied by the circumference is equal to r times r, measure the radius of the circle with a ruler, record it with a pen, and calculate it by inserting the formula.

The length of the circumference of a circle is the circumference of the circle. Two circles that can coincide are called equal circles, and equal circles have an infinite number of axes of symmetry. A circle is a regular n-sided (n is an infinitely large positive integer) with an infinitely long side close to 0 but can never be equal to 0.

An arc larger than a semicircle is called an excellent arc, and an arc smaller than a semicircle is called an inferior arc, so a semicircle is neither an excellent arc nor an inferior arc. The superior arc is generally represented by three letters, and the inferior arc is generally represented by two letters. The superior arc is the arc with the central angle of the opposite circle greater than 180 degrees, and the inferior arc is the arc with the central angle of the opposite circle less than 180 degrees.