Why use the perimeter to find the area of the ring

A ring is the area of the great circle minus the area of the small circle. Let the radius of the major circle be r and the radius of the minor circle be r, then the width of the circle is h=r-r

The area of the great circle is r and the area of the minor circle is r, then the area of the ring is r - r = (r -r) = (r+r)(r-r)=

This is the average of the circumferences of the two circles multiplied by the width of the rings. So this formula for the ring can be deduced, and that's how it is calculated.

The area of the garden ring can be subtracted by the area of the small circle on the outside by the large circle on the outside, that is:

s＝π(r²-r²)＝r＋r)(r-r)＝2π(r＋r)/2(r-r)

At this point, pay attention:

2 (p r) 2 is the average of the perimeter of the outer and inner gardens, r-r) is the width of the garden ring, and the product of the two is the area of the garden ring.

Let the circumference of the outer circle be l1

The circumference of the inner circle is L2

The radius of the outer circle is l1 (2).

The radius of the inner circle is l2 (2).

The area of the torus is = *(l1 2 (4 2)-l2 2 (4 2)) = (l1 2-l2 2) 4

If you count according to the arithmetic of the nine chapters.

The area of the torus is s=(l1+l2) 2*(l1 (2 )-l2 (2 ))=(l1 2-l2 2) 4

It's the same as the normal calculation method above.

The algorithm of the nine chapters of arithmetic should be regarded as a simple algorithm.

This question is calculated as follows:

The thick circumference of the semi-ring.

Circumference of a large semicircle Circumference of a small semicircle Difference in radius of a large and small semicircle 2 Circumference of a semicircle r, r is the radius.

Known: If the diameter of a large semicircle is 8, the radius is 4

If the diameter of the small semicircle is 6, then the radius is 3, substituting:

Circumference of the semi-circle.

Radical Town 3) 2

Semi-circular area Large semi-circular area Small semicircular area.

Semicircular area fingerprint r 2, substituting the known condition into:

Semi-torus area

Find the circumference and area of the Banchang Ring? Resistant to stalking.

The area of the semicircle is equal to the area of the large semicircle, and the remaining area minus the area of the small semicircle.

To find the area, first find the area of the outermost large circle, divide by 2 is the area of the large semicircle, and then find the area of the small circle in the middle, after dividing by 2 is the area of the small semicircle, the area of the large semicircle minus the area of the small semicircle, is the area of the semicircle, as follows: ((Sen stool 2)-(calculated is the area of the semicircle.

The circumference of the semi-circle is divided into half of the circumference of the major circle + half of the circumference of the minor circle + the circumference of the major circle minus the circumference of the small circle, which is the circumference of the semi-circle, as follows: (, the circumference of the semi-circle is calculated.

The length of the circumference of the semi-ring: c = chain filial piety 2 + 1 + 1 = cm;

The area of the semicircle evoking envy ring:

s= square centimeter.

The calculation idea in the question is correct.

The royal product of the torus is the area of the large semicircle and the area of the small semicircle.

Circumference of the round cherry plum ring Circumference of the large semicircle Circumference of the small semicircle Diameter of the large semicircle The diameter of the small semicircle The ridge is late.

Circumference of the semi-circle.

Half of the defeat of the ring of filial piety area Qiaopai Xiang:

It is known that the diameter of the great circle is 8 and the radius is 4; The diameter of the small circle is 6 and the radius is 3.

The formula for the circumference of a circle is: c= d=2 r

The circumference of the circle is equal to multiplied by the diameter of the circle. It is also equal to 2 times times the radius of the circle. (Generally, if not otherwise specified, =.)

c: chaotic macro indicates the circumference of the circle to be redirected; d: represents the diameter of the circle; r: represents the radius of the circle.

The formula for the area of a circle is the square of the radius of pi, which is represented by the letter nucleusable swim as: s= r or s= d2). Indicates pi (radius, d represents diameter).

The circumference of the semi-circle: half the circumference of the great circle + half the circumference of the minor circle + the diameter of the great circle - the diameter of the minor circle.

The area of the semi-circle: half of the area of the large circle - half the area of the small circle.

The radius of the great circle is 8 2=4 and the radius of the minor circle is 6 2=3

The area of the big orange circle is r 2=16 , and the area of the small circle is r 2=9 , so the area of the semicircle ring is 16 -9 =7 ,7 2=,

First calculate the area of the large semicircle outside, subtract the area of the small semicircle inside, the area of the dome is equal to the square of the radius, multiply by pie, the semicircle is one-half of the area before the mask, calculate the area of the large semicircle, subtract the area of the small semicircle to get the area of the shadow part.

The radius of the outer great circle is 4, the radius of the inner small circle is 3, and the circumference of the semi-circle is two arcs plus straight lines on both sides, so the circumference of the semi-circular ring ridge is: Wu * 4 Ten Wu * 3 Ten 2 (4-3) =

The area of the semicircle is the area of the large semicircle and the area of the semicircle is reduced: Yu hunger cavity (Wu * 4 2 a Wu * 3 2) 2 = (

Inner semicircle circumference: 6

The outer half of the ode does answer the circumference of the circle: 9

Ring width: 9-6=3 (cm) Naixun.

Circumference: 3 2 + 6 +9 = 6 + 15

Area (similar to Yehui trapezoid, ring width is equivalent to the height of the trapezoid, inner arc is equivalent to the upper bottom, outer arc is equivalent to the lower bottom):

Chang touches this 6 +9 ) 3 2=

I kept it, if you need Hu Shen to keep the decimals, you can substitute the noisy accounting.

The circumference is equal to the circumference of the minor circle + the circumference of the great circle, and the area is the area of the great circle minus the area of the minor circle.

The circumference of the semicircle is the arc length of the large semicircle plus the arc length of the small semicircle plus the diameter difference between the two semicircles, and the area of the semicircle is the area of the large semicircle and the area of the small semicircle.

Find the circumference of the semi-ring and the surface touching the silver product, the circumference of the semi-ring:

The arc length of the semicircle next to the large hermit plus the arc length of the small semicircle plus the difference between the diameters of the two oakers, 4*;

The area of the semi-ring: 4*4*.

The formula for the circumference of the semicircle is the circumference multiplied by the radius, i.e., the mountain elimination c = r. The formula for the area of the semicircle is the pi of the cong qi multiplied by half of the square of the radius, i.e., s = r 2.

The area and circumference of the semicircular ring is half of the circumference of the circle and the area of the finches, and the formula of the circle is calculated by the formula of the circle, and the circumference of the Senpi circle is deduced by the formula of the circle, which is the area of the two squares, and the difference is divided by the square of the two squares by two.

The inner and outer diameters of the semicircular ring are known. Now you only need to ask for the area of the outer diameter semicircle, and then subtract the area of the inner diameter semicircle, which is the area of the semicircle. The circumference is the inner diameter semi-circle plus the outer diameter semi-circle, and then the old one is accompanied by the difference between the outer diameter and the inner diameter.

The formula for the circumference of the semi-circle is = * inner circle radius Min Wangjin bridge base + outer circle radius) + (outer circle radius - inner circle radius) * 2

The formula for the area of a semicircular ring is = * square of the outer radius of the ring branch - square of the radius of the inner circle) 2

From the question, it is concluded that the radius of the large semicircle is 4, and the radius of the small semicircle is 3.

The area of the shadow of the yin circle stool is the area of the semicircle of the large cavity limb minus the area of the small semicircle.

s=1 2* *4 2-3 2) (here is only a semicircle, not the whole circle, to divide by Tsai Brigade 2) =

Circumference = (2 * 4 + 2 * 3) 2 + 1 + 1 = Here the circumference is also only a semicircle, to be divided by 2).

The circumferential long branches are equal to the length of the outer semicircular arc plus the length of the inner semicircular arc plus 2 times the width of the ring.

Area = 1 2 (square of the radius of the outer limb - square of the radius of the inner circle).

The circumference of the semicircle is equal to the circumference of the outer semicircle, plus the circumference of the inner semicircle. Then add the diameter of the outer semicircle minus the difference in diameter of the inner semicircle. The area of the semicircle is equal to the area of the y-semicircle minus the area of the inner semicircle.

First find out the inner circle and the outer circle of the Zhou Jin pretend to be filial piety, divided by two plus the difference between the diameters of the two circles, and the auspicious draft is the circumference. First find the area of the inner circle and the outer circle, and the area of the outer circle minus the area of the inner circle and divide by two, which is the area of the semicircle.

This problem is still very simple, we use Hunger Land.

The formula of radius is used to calculate the area of the large circle and the small circle respectively, and after they are subtracted, they are divided by two, which is the area of the ring.

The circumference of the semicircle is, and the formula for the area of the semicircle is Tanji: s= rr 2 ( square of the radius 2) The formula for the circumference of the semicircle is the late side: c = r + 2r (radius + diameter).

The calculation is as follows: the circumference of the semi-ring.

Half circumference of the great circle + half circumference of the small orange Chang Qi circle + diameter of the great circle - diameter of the small circle.

r+πr+2πr-2πr

The area of the semi-circular ring.

Large circle half area - small circle quickly defeated half area.

r²/2-πr²/2

The area of the semicircle is the area of the circle minus the area of the small halfcircle, and your calculation is the area of the large circle minus the area of the small circle, so the calculated answer needs to be divided by the area of the slippery 2 again, the area , take.

The circumference of the semicircular ring = centimeters.

The area of the semi-soji bridge ring = square centimeters.

Perimeter = large and small, only two semicircular arcs + two straight lines at the bottom.

is *3+4)+8-6

Area = Area of a large semicircle - Area of a small semicircle.

is 1 2 * 4 2 - 3 2).

The circumference of the semicircle is the circumference of the large circle, subtract the circumference of the small circle, then divide by two, add two centimeters, the area is the area of the large circle, subtract the surface of the small circle, and then divide by two.

Semi-Suspect Ring's Trouser Liquid Area Huwu = (Outer Circle R Squared - Inner Circle R Squared) 2

The formula for the circumference of a semicircle is p=r(+2).

Pi, r = outer ring radius, r = inner ring radius.

Formula: S-ring (R2-R2). Circles in circles: Wrapping shapes with unequal radii and concentric circles.

Ring area: outer circle area inner circle area (pi x square of large radius pi x square of small radius pi x square of large radius square of small radius). Formula: S-ring (R2-R2).

Introduction to the Ring. The rings in a circle are wrapping shapes with unequal radii and concentric circles. The symmetry of the ring is very strong, it is a central symmetrical figure with the center of the circle as the center of symmetry, and it is also an axisymmetric figure with countless axes of symmetry. The geometric center of the ring is the center of the circle.

The inversion of a geometric mean of the inner and outer radius centered on the center of the circle keeps the whole ring unchanged, interchanging the inner and outer edges, and interchanging the inner circle with the outer circle.

Circumference of the ring: the circumference of the outer circle The circumference of the inner circle Pi (large diameter small diameter).

The circumference of the ring = the circumference of the outer circle + the circumference of the inner circle, and the area of the ring = the area of the great circle (outer circle) - the area of the small circle (inner circle).

Circumference of the outer circle of the ring = 2 丌r;

circumference in the ring = 2 丌r;

Circle area = large circle area - small circle area.

2 丌 (r -r).

The area of the ring is calculated as the perimeter and volume:Let the radius of the outer circle be r and the radius of the inner circle be r

Circumference of the ring: 2 (r+r).

It is known that the outer diameter of the ring is d, and the thickness of the ring (i.e., the difference between the outer and inner radius) is dd=r-r

d-d=2r-(r-r)=r+r, and it is deduced that s= [(r-r) (r+r)]= (d-d) d torus area s= (d-d) d

A circle is a type of geometric shape.

By definition, a circle is usually drawn with a compass. The diameter and length of the radius of the circle within the same circle are always the same, and the circle has an infinite number of radii and an infinite number of diameters. A circle is an axisymmetric, center-symmetrical figure.

The axis of symmetry is the straight line where the diameter is located. At the same time, the circle is a "positive infinite polygon", and "infinity" is just a concept. A circle can be seen as a regular polygon composed of an infinite number of infinitesimal points, and the more sides of the polygon, the closer its shape, circumference, and area will be to the circle.

Characteristics of a circle: A circle is a closed figure made up of a curve, and the distance from any point on the circle to the center of the circle is equal.

The role of the center of the circle and the radius: the center of the circle determines the position of the circle, and the radius determines the size of the circle.

The circle is axisymmetric and the line with the diameter is the axis of symmetry of the circle. A circle has an infinite number of axes of symmetry.

The diameter in the same circle is 2 times the radius.

The circumference of a circle refers to the length of the curve that encloses the circle. The circumference of a circle with a large diameter is larger, and the circumference of a circle with a small diameter is smaller.

The quotient of the circumference of a circle divided by its diameter is a fixed number, which we call pi, which is denoted by , and is usually taken when calculating.

The circumference of the circle: c = 2 r or c = d

Find the radius: r=c 2

Find the diameter: d=c

The area of the circle is meaningful: the area of the circle is the area of the circle by the size of the plane occupied by the figure or the size of the surface of the round object.

The formula for calculating the area is: *r squared.

The area of the torus is calculated as follows: s = the square of r - the square of r or s= (the square of r - the square of r).

The circumference of the ring = the circumference of the outer circle of the large circle + the circumference of the inner circle of the small circle.

Ring area = outer circle area of the large circle - inner circle area of the small circle.

The area and perimeter of the ring are mainly calculated according to the known conditions, especially the radius of the inner and outer circles, or the radius of a known circle and the ratio of the inner and outer circles.

Ring area = outer circle area - inner circle area = 丌 (r -r).

The outer circumference of the ring = 2 丌r (r is the radius of the outer circle), and the inner circumference of the ring = 2 丌r (r is the radius of the inner circle).