How to find the circumference and area of a semicircle?

Answer: A semicircle is half of a circle.

The area of the circle = r 2, the area of the semicircle is half of it = (1 2) r 2 the circumference of the circle = 2 r, the circumference of the semicircle is multiple diameter length = r + 2r <>

Circumference: c = 2 r (r radius).

Area: s = r

Circumference of a semicircle: c = r + 2r

Semicircular area: s = r 2

Standard equation for a circle: In a planar Cartesian coordinate system, the standard equation for a circle with the point o(a,b) as the center and r as the radius is (x-a) 2+(y-b) 2=r 2.

General equation of the circle: After moving the standard equation of the circle and merging the similar terms, the general equation of the circle is x 2 + y 2 + dx + ey + f = 0. Compared with the standard equation, in fact, d = -2a, e = -2b, f = a 2 + b 2.

The positional relationship between the circle and the point: take the point p and the circle o as an example (let p be a point, then po is the distance from the point to the center of the circle), p is outside o, po r; p on o, po r; p in o, po r.

There are 3 positional relationships between lines and circles:

No common point is separated;

There are two common points that intersect;

A circle and a straight line have a single common point that is tangent, this straight line is called the tangent of the circle, and this only common point is called the tangent point.

Take the straight line ab and the circle o as an example (let op ab be in p, then po is the distance from ab to the center of the circle):

ab and o are separated, po r; ab is tangent to o, po r; ab intersects o and po r.

There are 5 positional relationships between two circles: if there is no common point, one circle is called alienation outside the other circle, and it is called containment within it; If there is a single common point, a circle outside another circle is called an external incision, and an internal incision is called an internal incision; There are two common points called intersection. The distance between the centers of two circles is called the center distance.

The radii of the two circles are r and r, and r r, and the center distance of the circle is p: outward p r+r; Exentom p=r+r; intersecting r-r p r+r; incision p=r-r; Contains p r-r.

1.Circumference formula for a semicircle =PiRadius + Diameter

It is represented by a letter formula as:

c half = r + 2r

2.The area formula for the semicircleThe formula for the area of a semicircle = pi and the square of the radius 2

The alphabetical formula is shown as follows:

S half = r2 2

3.The formula for the circumference of a circleCircumference of the circle = pi diameter of the circle = 2 pi radius of the circle.

It is represented by a letter formula as:

c= πd =2πr

4.The area formula for a circleThe area of the circle = the square of the radius of pi.

It is represented by a letter formula as:

s=πr^2

5.DefinitionsA semicircle is a figure surrounded by curves, it is half of a circle, and the position of the center of the semicircle is that it is a concentric circle.

The center of the circle has only one diameter, but has an infinite number of radii, and has an axis of symmetry.

The circumference of the semicircle = 2r + r Find the radius r and the area = 1 2 r 2.

Because the circumference of a semicircle is the circumference of a semicircle plus 2 radii. The circumference of the semicircle = r+2r, so, radius = the circumference of the semicircle (2).

And because the area of the circle = the square of the radius, the area of the circle = [the circumference of the semicircle (2)] if it is the area of the semicircle, divide it by 2.

Let the radius of the semicircle be r, then its circumference is l= r+2r; So if we know the perimeter l, then the radius r=l ( +2) and then substitute the area formula s= r 2=( l 2) ( +2) 2

The circumference of the semicircle = half of the circumference of the circle + the diameter.

That is: the circumference of the semicircle = pi radius + 2 radius = (pi + 2) radius so, radius = circumference of the semicircle (pi + 2).

After finding the radius, use the formula to find the area of the circle, and then divide by 2.

The circumference of the circle = 2 r

So knowing the perimeter, you can find the radius r=perimeter (2).

So the area = r can be found.

Know how to find the area of the circumference of the semicircle.

The circumference of the semicircle = r+2r

r=the circumference of the semicircle ( +2).

Area = 2*r 2 = 2*[circumference of a semicircle ( +2)] 2

Let the radius of the circle be r, then the circumference of the semicircle = r + 2r, solve the value of r, and then substitute the area of the semicircle = r 2.

The formula for calculating the area of a semicircle:

The area of the semicircle Pi x the square of the radius 2. Letter formula: s semicircle = r 2.

Explanation: The formula for the area of a circle is a law of the crack theorem, which is the square of pi x radius, which can be expressed by letters as: s= r or s= *d 2).

Indicates pi (radius, d represents diameter). The semicircle is half of the circle. When finding the circumference or area of a semicircle, it defaults to a closed figure, where its area is half the area of the complete circle, i.e.,

The area of the half-sail source front circle Pi x the square of the radius 2. Letter formula: s semicircle = r 2.

The circumference of the semicircle is equal to the sum of the radius and the circumference of the semicircle, i.e., r ten 丌r, and the area of the semicircle is 1 2 丌 r2

The circumference of the semicircle is equal to the sum of the radius multiplied by the radius; The area is equal to pi multiplied by radius squared divided by two.

It's okay to know the radius, the circumference of the half circle = the diameter of the half round * (2).

Semicircular Yundan Noodles Tongxin Product = Radius

Circumference: c = 2 r (r radius).

2.Area: s = r

3.Circumference of a semicircle: c = r + 2r

4.Semicircular area: s = r 2

5.Standard equation for a circle: In a planar Cartesian coordinate system, the standard equation for a circle with the point o(a,b) as the center and r as the radius is (x-a) 2+(y-b) 2=r 2.

6.General equation of the circle: After moving the standard equation of the circle and merging the similar terms, the general equation of the circle is x 2 + y 2 + dx + ey + f = 0. Compared with the standard equation, in fact, d = -2a, e = -2b, f = a 2 + b 2.

7.The positional relationship between the circle and the point: take the point p and the circle o as an example (let p be a point, then po is the distance from the point to the center of the circle), p is outside o, po r; p on o, po r; p in o, po r.

8.There are three positional relationships between straight lines and circles: no common point is separated; There are two common points that intersect; The circle and the straight line have a single common point to be tangent, this straight line is called the tangent of the circle, and this only common point is called the tangent point.

Take the line ab and the circle o as an example (let op ab be in p, then po is the distance from ab to the center of the circle): ab and o are separated, po r; ab is tangent to o, po r; ab intersects o and po r.

The formula for the area of a semicircle is, s= r 2 2 ( square of radius 2) and the formula for the circumference of a semicircle is, c = r + 2r (radius + diameter). where the area is half of the circle, and the circumference is the length of the arc plus the diameter.

In mathematics (especially in the geometry of acres), a semicircle is a one-dimensional trajectory of points that form a half-circle. The arc of a semicircle is always measured at 180° (equivalent to an arc or half a circle). It has only one line of symmetry (reflective symmetry).

The two endpoints of any diameter of the circle divide the circle into two arcs, each of which is called a semicircle. The semicircle is to be separated from the semicircle, because the half-circle is just an arc. It is the vertical half of the circle, and the position of the center of the semicircle is the position of the center of its concentric circles, which has only one diameter, but has an infinite number of radii, and has an axis of symmetry.

Circumference: c = 2 r (r radius).

Area: s = r

Circumference of a semicircle: c = r + 2r

Semicircular area: s = r 2

The circumference of the circle = 2 r, so the circumference of the semicircle = 2 r 2+2r = r + 2r, and the area of the semicircle = r 2

The circumference of a semicircle is half the circumference of the circle plus the diameter.

The area of the semicircle is half the area of the circle.